Apparatus for inspecting circuit board and method of inspecting circuit board

ABSTRACT

An apparatus and method for inspecting a circuit board is described which can well absorb a variation in a height of an electrode to be inspected and can maintain an insulating property between adjacent inspection electrodes even if the electrode to be inspected is arranged at a fine pitch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of Ser. No. 11/632,287,filed Jan. 12, 2007, the entire contents of which is incorporated hereinby reference. U.S. Ser. No. 11/632,287 is the National Stage Applicationof PCT/JP05/13043, filed on Jul. 14, 2005, which is based upon andclaims benefit of priority from the prior Japanese Patent ApplicationNo. 2004-208555, filed on Jul. 14, 2004.

TECHNICAL FIELD

The present invention relates to an apparatus for inspecting a circuitboard and a method of inspecting a circuit board which interpose acircuit board to be an inspecting target which is to be electricallyinspected (which will be hereinafter referred to as a “a circuit boardto be inspected”) by pressure from both sides by means of a pair offirst and second inspecting jigs, thereby bringing a state in whichelectrodes formed on both sides of the circuit board to be inspected areconnected electrically to a tester to inspect the electricalcharacteristics of the circuit board to be inspected.

BACKGROUND ART

Referring to a printed circuit board for mounting an integrated circuitor the like, electrical characteristics are inspected to confirm thatthe wiring pattern of the circuit board has a predetermined performancebefore mounting the integrated circuit or the like.

In the electrical inspection, for example, an inspecting head isincorporated into an inspecting tester including the delivery mechanismof the circuit board and inspecting head portions are exchanged toinspect different circuit boards.

For example, as is disclosed in Patent Document 1 (Japanese Laid-OpenPatent Publication No. 1994-94768), there has been proposed a methodusing an inspecting jig having a structure in which a metallicinspecting pin to be electrically conducted in contact with an electrodeto be inspected in a circuit board to be inspected is infixed into aboard.

As is disclosed in Patent Document 2 (Japanese Laid-Open PatentPublication No. 1993-159821), moreover, there has been known a methodusing an inspecting jig in which an inspecting head having a conductivepin, a circuit board for pitch conversion which is referred to as anoff-grid adapter and an anisotropically conductive sheet are combined.

In the method using an inspecting jig to cause a metallic inspecting pinto directly come in contact with the electrode to be inspected in thecircuit board to be inspected as described in the Patent Document 1(Japanese Laid-Open Patent Publication No. 1994-94768), however, thereis a possibility that the electrode of the circuit board to be inspectedmight be damaged due to the contact with the conductive pin formed of ametal.

In recent years, particularly, the fineness and density of a circuit inthe circuit board has been increased. In the case in which such aprinted circuit board is to be inspected, it is necessary to pressurizean inspecting jig at a high pressure in order to cause a large number ofconductive pins to be simultaneously conducted in contact with anelectrode to be inspected in a circuit board to be inspected.Consequently, the electrode to be inspected is apt to be damaged.

In an inspecting jig for inspecting the printed circuit board having thefineness and density increased, it has been technically hard to infix alarge number of metallic pins into the board at a high density.Moreover, a manufacturing cost is also increased. In the case in which apart of the metallic pins are damaged, furthermore, it is hard to repairor exchange them.

On the other hand, in the inspecting jig using the anisotropicallyconductive sheet as described in the Patent Document 2 (JapaneseLaid-Open Patent Publication No. 1993-159821), the electrode to beinspected in the circuit board to be inspected comes in contact with theelectrode of the board for pitch conversion through the anisotropicallyconductive sheet. Therefore, there is an advantage that the electrode tobe inspected in the circuit board to be inspected is damaged withdifficulty. Moreover, the board for carrying out the pitch conversion isused. Therefore, the inspecting pin to be infixed into the board can beinfixed at a greater pitch than the pitch of the electrode to beinspected in the circuit board to be inspected. For this reason, it isnot necessary to infix the inspecting pin at a minute pitch.Consequently, there is also an advantage that the manufacturing cost ofthe inspecting jig can be reduced.

In the inspecting jig, however, it is necessary to create the board forpitch conversion and the inspecting jig for infixing the inspecting pinfor each circuit board to be inspected which is the inspecting target.Therefore, the same number of inspecting jigs as that of the printedcircuit boards which are the circuit boards to be inspected arerequired.

In the case in which a plurality of printed circuit boards is produced,therefore, there is a problem in that a plurality of inspecting jigs isto be retained corresponding thereto. In recent years, particularly, themanufacturing cycle of an electronic apparatus has been shortened and areduction in the production period of a printed circuit board to be usedin a product has been progressed. Consequently, the inspecting jigcannot be used for a long period of time. Thus, there is a problem inthat the inspecting jig is to be produced every time the production ofthe printed circuit board is changed over.

For a countermeasure against such problems, for example, there has beenproposed an inspecting apparatus using an inspecting jig of a so-calleduniversal type using a relay pin unit disclosed in Patent Documents 3 to5 (Japanese Laid-Open Patent Publication No. 1995-248350, JapaneseLaid-Open Patent Publication No. 1996-271569 and Japanese Laid-OpenPatent Publication No. 1996-338858).

FIG. 36 is a sectional view showing the inspecting apparatus using theinspecting jig of a universal type. The inspecting apparatus comprises apair of first and second inspecting jigs 111 a and 111 b, and theseinspecting jigs include circuit board side connectors 121 a and 121 b,relay pin units 131 a and 131 b, and tester side connectors 141 a and141 b.

The circuit board side connectors 121 a and 121 b include boards 123 aand 123 b for pitch conversion, and anisotropically conductive sheets122 a, 122 b, 126 a and 126 b provided on both sides thereof.

The relay pin units 131 a and 131 b include a large number of conductivepins 132 a and 132 b (for example, 5000 pins) provided on a latticepoint at a constant pitch (for example, a pitch of 2.54 mm), and a pairof insulating plates 134 a and 134 b for supporting the conductive pins132 a and 132 b to be vertically movable.

The tester side connectors 141 a and 141 b include connector boards 143a and 143 b for electrically connecting the testers to the conductivepins 132 a and 132 b when interposing the circuit board 101 to beinspected between the inspecting jigs 111 a and 111 b by pressure,anisotropically conductive sheets 142 a and 142 b provided on the sidesof the conductive pins 132 a and 132 b of the connector boards 143 a and143 b, and base plates 146 a and 146 b.

When the inspecting jig using the relay pin unit is to inspect printedcircuit boards which are different targets to be inspected, it issufficient that the circuit board side connectors 121 a and 121 b areexchanged with members corresponding to the circuit board 101 to beinspected, and the relay pin units 131 a and 131 b and the tester sideconnectors 141 a and 141 b can be used in common.

The printed wiring board to be the circuit board 101 to be inspected hasbeen multilayered and increased in a density. A variation in a heightand a warpage of the board itself are actually caused by the electrodes102 and 103 to be inspected, for example, a solder ball electrode suchas a BGA in the direction of a thickness. In order to achieve anelectrical connection to the electrodes 102 and 103 to be inspectedwhich are inspecting points on the circuit board 101 to be inspected,therefore, it is necessary to pressurize the first inspecting jig 111 aand the second inspecting jig 111 b at a high pressure, thereby flatlydeforming the circuit board 101 to be inspected, and it is necessary tocause the variation in the heights of the electrodes 102 and 103 to beinspected to follow the heights of the electrodes 102 and 103 to beinspected on the sides of the first inspecting jig 111 a and the secondinspecting jig 111 b.

In the conventional inspecting jig of a universal type, the heights ofthe electrodes 102 and 103 to be inspected are followed by a movement inthe axial direction of the conductive pins 132 a and 132 b in order tomaintain a follow-up for the same heights. However, the amount of themovement in the axial direction of the conductive pins 132 a and 132 balso has a restriction. For this reason, the follow-up for the heightsof the electrodes 102 and 103 to be inspected is not excellent in somecases. Consequently, a defective conduction is generated so that anaccurate inspection cannot be carried out.

In the inspecting jig of a universal type, moreover, a press pressure inthe case in which the circuit board 101 to be inspected is interposed bypressure between the first inspecting jig 111 a and the secondinspecting jig 111 b is absorbed into the upper and loweranisotropically conductive sheets 122 a, 122 b, 126 a, 126 b, 142 a and142 b.

In the inspecting jig of a universal type, therefore, it is necessary toarrange the conductive pins 132 a and 132 b at a constant interval inorder to support the boards 123 a and 123 b for pitch conversion and todisperse the press pressure.

In the conventional inspecting jig of a universal type, moreover, thepress pressure is received by the conductive pins 132 a and 132 b. Forthis reason, it is necessary to arrange a large number of conductivepins 132 a and 132 b at a constant interval.

In some cases in which the insulating plates 134 a and 134 b having atleast 10000 through holes are to be formed at a pitch of 0.75 mm, forexample, corresponding to the microfabrication of the electrode of thecircuit board 101 to be inspected, therefore, strengths are reduced ifthe thicknesses of the boards of the insulating plates 134 a and 134 bare small and they are broken due to bending. For this reason, it isnecessary to increase the thicknesses of the insulating plates 134 a and134 b.

If the through hole to be formed is fine, for example, has a diameter ofapproximately 0.5 mm and the insulating plates 134 a and 134 b havethicknesses of 5 mm or more, however, a blade of a drill is defectiveand broken to fail in the processing of the insulating plate in respectof a strength of the blade of the drill in many cases in which thethrough hole is to be formed by one drill processing.

For this reason, the drill processing is carried out to almost a half ofa thickness from either surface of the insulating plate, andfurthermore, is carried out in the same portion from the other surfaceside to form the through hole, thereby processing the insulating plate.In this case, there is a problem in that a drill processing work to be adouble of the number of the through holes to be formed on the insulatingplate is required and the processing step is thus complicated.

In the conventional inspecting jig of a universal type, moreover, thereare used, as the anisotropically conductive sheets 122 a and 122 bconstituting the circuit board side connectors, the anisotropicallyconductive sheets of an uneven distribution type which include aplurality of conductive path forming portions extended in the directionof a thickness and insulating portions for insulating these conductivepath forming portions from each other and in which conductive particlesare contained in only the conductive path forming portion and aredistributed unevenly in a planar direction, and the conductive pathforming portion is protruded toward the either surface side of thesheet. In the case in which the conductive path forming portion isdeteriorated (a resistance value is increased) by a repetitive use in aninspection and the anisotropically conductive sheet is exchanged, it isnecessary to align the anisotropically conductive sheet with the boardfor pitch conversion and to align the circuit board side connector withthe relay pin unit every exchange. The aligning work is complicated tocause a reduction in an inspection efficiency.

When the electrodes in the circuit board are arranged at a minute pitchof 200 μm or less, for example, it is easy to generate the positionalshift of the anisotropically conductive sheet due to a repetitivecontact with a plurality of circuit boards in the case in which thecircuit boards are continuously inspected by using the anisotropicallyconductive sheet described above. Consequently, the conductive pathforming portion of the anisotropically conductive sheet and the positionof the electrode in the circuit board are not coincident with each otherso that an excellent electrical connection cannot be obtained. For thisreason, an excessively great resistance value is measured so that aprinted circuit board to be originally decided to be an excellentproduct is easily decided erroneously to be a defective product.

In the case in which there is obtained an anisotropically conductiveelastomer sheet of an uneven distribution type for inspecting thecircuit board having the electrodes to be inspected which are disposedat a small pitch in a distance of 10 μm or less between the electrodesto be inspected, moreover, it is necessary to carry out a formation insuch a manner that a width of the insulating portion for mutuallyinsulating the adjacent conductive path forming portions is equal to orsmaller than 100 μm. In a conventional method of manufacturing a sheetby metal molding which has been disclosed in Patent Document 6 (JapaneseLaid-Open Patent Publication No. 1991-196416), for example, it is hardto form the insulating portion having a width of 100 μm or less becauseof a magnetic field action with an adjacent metal mold magnetic pole. Inthe anisotropically conductive elastomer sheet of an uneven distributiontype according to the conventional manufacturing method, therefore, alower limit of the distance between the electrodes of the circuit boardat which the inspection can be carried out is approximately 80 to 100 μmdepending on a thickness of the sheet.

For this reason, it is very hard to form, by the metal molding method,the anisotropically conductive elastomer sheet of an uneven distributiontype for inspecting the circuit board having the inspected electrodesdisposed at a small pitch in which the distance between the inspectedelectrodes is equal to or smaller than 50 μm. Consequently, theanisotropically conductive elastomer sheet of an uneven distributiontype has not been obtained substantially.

On the other hand, it is possible to obtain a high resolution byreducing a thickness of a so-called anisotropically conductive elastomersheet of a dispersion type in which conductive particles are arranged ina direction of a thickness and are uniformly dispersed in a planardirection. Therefore, it is possible to inspect the circuit board inwhich the distance between the electrodes to be inspected is equal to orsmaller than 50 μm in the resolution by setting a thickness ofapproximately 30 μm, for example.

In a thin anisotropically conductive elastomer sheet of a dispersiontype which has a thickness of approximately 30 μm, however, theabsorption of a mechanical shock generated by an elasticity of a sheetbody or a capability for constituting an electrical connection to becarried out by a soft contact of electrodes which is one ofcharacteristics of the anisotropically conductive elastomer sheet iseliminated almost completely. In the case in which a circuit board to beinspected which includes a large number of inspected electrodes having avariation in a height is connected to the inspecting apparatus,therefore, it is hard to connect a large number of inspected electrodesat the same time due to a reduction in a step absorbing capability ofthe anisotropically conductive elastomer sheet. For example, in acircuit board in which a large number of electrodes are formed byplating, a variation in a height of each of the electrodes isapproximately 20 μm.

In the anisotropically conductive elastomer sheet of a dispersion type,a compressibility capable of stably achieving an electrical conductionis equal to or smaller than approximately 20% in a compression in adirection of a thickness. For example, when the compression is carriedout beyond 20%, the electrical conduction in a transverse direction isincreased so that an anisotropy of the conduction is deteriorated, andfurthermore, a permanent deformation of the elastomer to be a basematerial is generated so that a repetitive use is hard to perform. Forthis reason, in the case in which the circuit board including theelectrode having the variation in a height of approximately 20 μm is tobe inspected, it is necessary to use the anisotropically conductiveelastomer sheet of a dispersion type which has a thickness of 100 μm ormore.

When the anisotropically conductive elastomer sheet of a dispersion typewhich has a thickness of 100 μm or more is used, however, there is aproblem in that it is substantially impossible to inspect a circuitboard having electrodes to be inspected which are disposed at a smallpitch of 50 μm or less because of a deterioration in a resolution.

In an anisotropically conductive elastomer sheet of a dispersion typewhich has a small thickness, furthermore, a capability for absorbing amechanical shock is small because of a small elasticity of a sheet body.In a use for an adaptor for inspecting a circuit board to repetitivelyinspect the circuit board, the anisotropically conductive elastomersheet is deteriorated quickly. For this reason, the anisotropicallyconductive elastomer sheet of a dispersion type is to be exchanged oftenso that an exchanging work is complicated and an inspection efficiencyfor the circuit board is reduced.

From the foregoing, in the circuit board inspecting adaptor using theanisotropically conductive elastomer sheet which serves to inspect thecircuit board having the electrodes to be inspected that are disposed ata small pitch of 50 μm or less, all of a resolution, a step absorbingpower and a repetitive use durability cannot be satisfied.

In the case in which a four-terminal inspection is carried out in orderto detect a latent electrical defect of the circuit board with highprecision, furthermore, two inspection electrodes (for a voltage and acurrent) of the circuit board for an inspection are connected to one ofthe electrodes to be inspected in the circuit board to be inspected. Forthis reason, a distance between the inspection electrodes to make a pairof the circuit board for an inspection is decreased. For example, in thecase in which the pitch between the electrodes to be inspected in thecircuit board to be inspected is 200 μm, a diameter of the electrode tobe inspected is approximately 100 μm and two inspection electrodes ofthe circuit board for an inspection are connected to the electrode to beinspected which has a diameter of approximately 100 μm. Therefore, thedistance between the inspection electrodes of the circuit board for aninspection is approximately 30 to 40 μm.

As described above, in the conventional anisotropically conductive sheetof an uneven distribution type or anisotropically conductive sheet of adispersion type, it is impossible to sufficiently obtain all of aresolution, a step absorbing power, a cushioning property and adurability with respect to an inspecting apparatus for inspecting acircuit board having a large number of electrodes to be inspected.

Patent Document 1: Japanese Laid-Open Patent Publication No. 1994-94768Patent Document 2: Japanese Laid-Open Patent Publication No. 1993-159821Patent Document 3: Japanese Laid-Open Patent Publication No. 1995-248350Patent Document 4: Japanese Laid-Open Patent Publication No. 1996-271569Patent Document 5 Japanese Laid-Open Patent Publication No. 1996-338858Patent Document 6: Japanese Laid-Open Patent Publication No. 1991-196416DISCLOSURE OF THE INVENTION Problems to be Solved

The present invention has been made to solve the problems of the priorart described above and has an object to provide an apparatus forinspecting a circuit board and a method of inspecting a circuit boardwhich can electrically inspect a circuit board with a high reliabilityeven if a circuit board to be inspected which is an inspecting targethas a minute electrode arranged at a fine pitch.

Moreover, it is an object of the present invention to provide anapparatus for inspecting a circuit board and a method of inspecting acircuit board which have an excellent follow-up for a height withrespect to a variation in the height of an electrode to be inspected ina circuit board to be inspected which is an inspecting target and canexecute an accurate inspection without generating a defectiveconduction.

Furthermore, it is an object of the present invention to provide anapparatus for inspecting a circuit board and a method of inspecting acircuit board in which a concentration of a stress in an inspection foran anisotropically conductive sheet is dispersed well and a durabilityto a repetitive use is excellent.

In addition, it is an object of the present invention to provide anapparatus for inspecting a circuit board which does not need to disposea conductive pin at a regular interval and can thus lessen a work forproviding a through hole on an insulating plate to hold the conductivepin through a drill processing, thereby reducing a cost.

Moreover, it is an object of the present invention to provide anapparatus for inspecting a circuit board and a method of inspecting acircuit board which can carry out an inspection with a high resolutionand can absorb a step generated by an electrode to be inspected in acircuit board to be inspected well, and are also excellent in adurability to a repetitive use of an anisotropically conductive sheet.

Means for Solving the Problems

The present invention provides an apparatus for inspecting a circuitboard which interposes both sides of a circuit board to be inspectedthat is an inspecting target between a pair of first and secondinspecting jigs by pressure by means of both of the inspecting jigs,thereby carrying out an electrical inspection,

each of the first inspecting jig and the second inspecting jigincluding:

a circuit board side connector having:

-   -   a board for pitch conversion which converts an electrode pitch        between one of surface sides of the board and the other surface        side;    -   a relay board disposed on a side of the circuit board to be        inspected in the board for pitch conversion, having a plurality        of rigid conductor electrodes penetrating through the board        which is held to be movable in a direction of a thickness of the        board, and serving to relay an electrical connection of an        inspection electrode of the board for pitch conversion and an        electrode to be inspected in the circuit board to be inspected        through the rigid conductor electrodes;    -   a pair of first anisotropically conductive sheets disposed on        one surface side and the other surface side of the relay board        and having a conductive particle arranged in a direction of a        thickness and distributed uniformly in a planar direction; and    -   a second anisotropically conductive sheet provided on a reverse        side to the circuit board to be inspected in the board for pitch        conversion;

a relay pin unit having:

-   -   a plurality of conductive pins provided at a predetermined        pitch; and    -   a pair of first and second insulating plates which are separated        from each other and serve to support the conductive pins movably        in an axial direction; and

a tester side connector having:

-   -   a connector board for electrically connecting a tester to the        relay pin unit;    -   a third anisotropically conductive sheet provided on the relay        pin unit side of the connector board; and    -   a base plate provided on a reverse side to the relay pin unit of        the connector board,

wherein the relay pin unit has:

-   -   an intermediate holding plate provided between the first        insulating plate and the second insulating plate;    -   a first support pin provided between the first insulating plate        and the intermediate holding plate; and    -   a second support pin provided between the second insulating        plate and the intermediate holding plate, and

a first abutment support position of the first support pin with respectto the intermediate holding plate and a second abutment support positionof the second support pin with respect to the intermediate holding plateare placed differently from each other over an intermediate holdingplate projecting surface which is projected in a direction of athickness of the intermediate holding plate.

In a preferred aspect of the invention, a plurality of through holes isformed on the board in the relay board, an insulating portion formed bya polymeric elastic body is formed in the through holes, and the rigidconductor electrode penetrates through the insulating portion and isheld to be movable in the direction of the thickness of the board bymeans of the insulating portion.

In another preferred aspect of the invention, the board in the relayboard has an insulating property and a plurality of through holes isformed on the board,

the rigid conductor electrode includes a drum portion inserted in thethrough holes and a terminal portion formed on both ends of the drumportion and having a larger diameter than a diameter of the throughhole, and

the rigid conductor electrode is held in the through hole of the boardso as to be movable in the direction of the thickness of the board.

In the invention, when both sides of the circuit board to be inspectedwhich is the inspecting target are to be interposed by pressure betweenthe first inspecting jig and the second inspecting jig to carry out theelectrical inspection, it is possible to absorb a pressure by a movementin the direction of a thickness by the conductive pin of the relay pinunit and the rubber elastic compression of the first anisotropicallyconductive sheet, the second anisotropically conductive sheet and thethird anisotropically conductive sheet in the initial stage of thepressurization, thereby absorbing a variation in the height of theelectrode to be inspected in the circuit board to be inspected to somedegree.

The first abutment support position of the first support pin withrespect to the intermediate holding plate and the second abutmentsupport position of the second support pin with respect to theintermediate holding plate are provided differently from each other overthe intermediate holding plate projecting surface which is projected inthe direction of the thickness of the intermediate holding plate. Whenthe circuit board to be inspected which is the inspecting target isfurther pressurized between the first inspecting jig and the secondinspecting jig, therefore, it is possible to disperse the concentrationof a pressure with respect to the variation in the height of theelectrode to be inspected in the circuit board to be inspected, forexample, a variation in the height of a solder ball electrode by thespring elasticity of the first insulating plate, the second insulatingplate and the intermediate holding plate provided between the firstinsulating plate and the second insulating plate in the relay pin unitin addition to the rubber elastic compression of the firstanisotropically conductive sheet, the second anisotropically conductivesheet and the third anisotropically conductive sheet, thereby avoidingthe local concentration of a stress.

Consequently, a stable electrical contact can be maintained, andfurthermore, the concentration of a stress can be reduced for each ofthe electrodes to be inspected in the circuit board to be inspectedwhich have the variation in the height. Therefore, it is possible tosuppress the local breakage of the anisotropically conductive sheet. Asa result, it is possible to enhance a durability to the repetitive useof the anisotropically conductive sheet. Consequently, the number ofexchanges of the anisotropically conductive sheet can be decreased andthe efficiency of an inspecting work can be enhanced.

Moreover, it is not necessary to dispose the conductive pin at a regularinterval. Therefore, it is possible to lessen a work for providing athrough hole on the insulating plate holding the conductive pin througha drill processing, thereby reducing a cost.

In the present invention, furthermore, the relay board in which aplurality of rigid conductor electrodes penetrating through the board isheld to be movable in the direction of the thickness of the board isdisposed between the circuit board to be inspected and the board forpitch conversion, and the anisotropically conductive elastomer sheet ofa dispersion type is provided on both sides of the relay board.

For this reason, even if the thicknesses of the respectiveanisotropically conductive elastomer sheets of a dispersion type aredecreased to obtain a sufficient resolution corresponding to theelectrodes to be inspected which are arranged at a fine pitch, it ispossible to fully absorb the step of the electrodes to be inspected inthe circuit board to be inspected by these two anisotropicallyconductive elastomer sheets of a dispersion type and to stably connect alarge number of electrodes to be inspected. Moreover, a mechanical shockis sufficiently absorbed. Therefore, a durability to a repetition of theanisotropically conductive elastomer sheet of a dispersion type is highand the anisotropically conductive elastomer sheet of a dispersion typedoes not need to be exchanged often. Consequently, the inspectionefficiency of the circuit board to be inspected can be enhanced.

Furthermore, the rigid conductor electrode is held to be movable in thedirection of the thickness of the board. Therefore, the step of theelectrode to be inspected in the circuit board to be inspected can alsobe absorbed by the relay board. Thus, it is possible to relieve thelocal concentration of a stress on the anisotropically conductiveelastomer sheet of a dispersion type.

The apparatus for inspecting a circuit board according to the presentinvention is characterized in that when the both sides of the circuitboard to be inspected which is the inspecting target are interposed bypressure between the pair of first and second inspecting jigs by meansof both of the inspecting jigs,

the intermediate holding plate is flexed in a direction of the secondinsulating plate around the first abutment support position of the firstsupport pin with respect to the intermediate holding plate, and

the intermediate holding plate is flexed in a direction of the firstinsulating plate around the second abutment support position of thesecond support pin with respect to the intermediate holding plate.

By such a structure, the intermediate holding plate is flexed mutuallyin opposite directions around the first abutment support position andthe second abutment support position. When the circuit board to beinspected which is the inspecting target is further pressurized betweenthe first inspecting jig and the second inspecting jig, therefore, thespring elastic force of the intermediate holding plate is exhibited moregreatly. Consequently, it is possible to disperse the concentration of apressure with respect to a variation in the height of the electrode tobe inspected in the circuit board to be inspected, thereby avoiding thelocal concentration of a stress. Thus, it is possible to suppress thelocal breakage of the anisotropically conductive sheet. As a result, thedurability to the repetitive use of the anisotropically conductive sheetcan be enhanced. Consequently, the number of exchanges of theanisotropically conductive sheet can be decreased so that the efficiencyof an inspecting work can be enhanced.

The apparatus for inspecting a circuit board according to the presentinvention is characterized in that the first abutment support positionof the first support pin with respect to the intermediate holding plateis placed like a lattice on the intermediate holding plate projectingsurface,

the second abutment support position of the second support pin withrespect to the intermediate holding plate is placed like a lattice onthe intermediate holding plate projecting surface,

one second abutment support position is placed in a unit lattice regionconstituted by four adjacent first abutment support positions in theintermediate holding plate projecting surface, and

one first abutment support position is placed in a unit lattice regionconstituted by four adjacent second abutment support positions in theintermediate holding plate projecting surface.

By such a structure, the first abutment support position and the secondabutment support position are placed like the lattice, and furthermore,all of the positions of lattice points in the first abutment supportposition and the second abutment support position are arranged with ashift.

Accordingly, the intermediate holding plate is flexed mutually in theopposite directions around the first abutment support position and thesecond abutment support position. When the circuit board to be inspectedwhich is the inspecting target is pressurized between the firstinspecting jig and the second inspecting jig, consequently, the springelastic force of the intermediate holding plate is further exhibited.Thus, it is possible to disperse the concentration of a pressure withrespect to a variation in the height of the electrode to be inspected inthe circuit board to be inspected, thereby avoiding the localconcentration of a stress still more. Accordingly, it is possible tosuppress the local breakage of the anisotropically conductive sheet. Asa result, the durability to the repetitive use of the anisotropicallyconductive sheet can be enhanced. Consequently, the number of exchangesof the anisotropically conductive sheet can be decreased so that theefficiency of an inspecting work can be enhanced.

Moreover, the apparatus for inspecting a circuit board according to thepresent invention is characterized in that the relay pin unit includes:

a plurality of intermediate holding plates provided apart from eachother at a predetermined interval between the first insulating plate andthe second insulating plate; and

a holding plate support pin provided between the adjacent intermediateholding plates, and

in at least one of the intermediate holding plates, an abutment supportposition of the holding plate support pin to abut on the intermediateholding plate from one surface side with respect to the intermediateholding plate and an abutment support position of a first support pin, asecond support pin or the holding plate support pin to abut on theintermediate holding plate from the other surface side with respect tothe intermediate holding plate are placed differently from each otherover the intermediate holding plate projecting surface which isprojected in the direction of the thickness of the intermediate holdingplate.

By such a structure, the spring elasticity is further exhibited by theseintermediate holding plates. Consequently, it is possible to dispersethe concentration of a pressure with respect to a variation in theheight of the electrode to be inspected in the circuit board to beinspected, thereby avoiding the local concentration of a stress stillmore. Thus, it is possible to suppress the local breakage of theanisotropically conductive sheet. As a result, the durability to therepetitive use of the anisotropically conductive sheet can be enhanced.Consequently, the number of exchanges of the anisotropically conductivesheet can be decreased so that the efficiency of an inspecting work canbe enhanced.

Furthermore, the apparatus for inspecting a circuit board according tothe present invention is characterized in that in all of theintermediate holding plates, the abutment support position of theholding plate support pin to abut on the intermediate holding plate fromone surface side with respect to the intermediate holding plate and theabutment support position of the first support pin, the second supportpin or the holding plate support pin to abut on the intermediate holdingplate from the other surface side with respect to the intermediateholding plate are placed differently from each other over theintermediate holding plate projecting surface which is projected in thedirection of the thickness of the intermediate holding plate.

Consequently, the abutment support position of the holding plate supportpin on the intermediate holding plate is shifted between the adjacentintermediate holding plates. Therefore, the spring elasticity of theseintermediate holding plates is further exhibited. Thus, it is possibleto disperse the concentration of a pressure with respect to a variationin the height of the electrode to be inspected in the circuit board tobe inspected, thereby avoiding the local concentration of a stress stillmore. Consequently, it is possible to suppress the local breakage of theanisotropically conductive sheet. As a result, the durability to therepetitive use of the anisotropically conductive sheet can be enhanced.Consequently, the number of exchanges of the anisotropically conductivesheet can be decreased so that the efficiency of an inspecting work canbe enhanced.

Moreover, the apparatus for inspecting a circuit board according to thepresent invention is characterized in that the second anisotropicallyconductive sheet is constituted by a plurality of conductive pathforming portions extended in a direction of a thickness and aninsulating portion for insulating these conductive path forming portionsfrom each other, and a conductive particle is contained in only theconductive path forming portions so that it is dispersed nonuniformly ina planar direction, and the conductive path forming portions areprotruded from either side of the sheet.

Furthermore, the apparatus for inspecting a circuit board according tothe present invention is characterized in that the third anisotropicallyconductive sheet is constituted by a plurality of conductive pathforming portions extended in a direction of a thickness and aninsulating portion for insulating these conductive path forming portionsfrom each other, and a conductive particle is contained in only theconductive path forming portions so that it is dispersed nonuniformly ina planar direction, and the conductive path forming portions areprotruded from either side of the sheet.

As the second anisotropically conductive sheet and the thirdanisotropically conductive sheet, thus, there is used theanisotropically conductive sheet of an uneven distribution type which isconstituted by the conductive path forming portion and the insulatingportion, has the conductive particle contained in only the conductivepath forming portion and distributed unevenly in the planar direction,and has the conductive path forming portion protruded toward eithersurface side of the sheet. Consequently, a pressurizing force and ashock generated by the press of the inspecting jig are absorbed by thesesheets. Thus, it is possible to suppress a deterioration in the firstanisotropically conductive sheet.

In an aspect of the present invention, each of the conductive pinsincludes a bar-shaped central part which is shorter than an intervalbetween the first insulating plate and the second insulating plate and apair of ends formed on both end sides of the central part and havingsmaller diameters than the central part, and

each of the ends is inserted in a through hole formed on the firstinsulating plate and the second insulating plate and having a smallerdiameter than the central part and a larger diameter than the pair ofends, thereby supporting the conductive pin to be movable in an axialdirection.

By such a structure, the conductive pin can be held movably in the axialdirection between the first insulating plate and the second insulatingplate so as not to slip off.

In another aspect of the present invention, a bending and holding plateprovided with a through hole for inserting the conductive pin therein isdisposed between the first insulating plate and the intermediate holdingplate, between the second insulating plate and the intermediate holdingplate, or between the intermediate holding plates, and

the conductive pins are pressed in transverse directions which areopposite to each other by setting, as fulcrums, the through hole formedon the first and second insulating plates and the through hole formed onthe bending and holding plate and are bent in a position of the throughhole of the bending and holding plate so that the conductive pin issupported to be movable in an axial direction.

By such a structure, the conductive pin can be held movably in the axialdirection between the first insulating plate and the second insulatingplate so as not to slip off. Furthermore, a pin taking a cylindricalshape and having a simple structure can also be used as the conductivepin. Therefore, it is possible to reduce the cost of the conductive pinand the member for holding the same as a whole.

The present invention provides a method of inspecting a circuit boardusing the apparatus for inspecting a circuit board described above,

wherein both sides of a circuit board to be inspected which is aninspecting target are interposed by pressure between a pair of first andsecond inspecting jigs by means of both of the inspecting jigs, therebycarrying out an electrical inspection.

By such a structure, the local breakage of the anisotropicallyconductive sheet can be suppressed. As a result, the durability to therepetitive use of the anisotropically conductive sheet can be enhanced.Consequently, the number of exchanges of the anisotropically conductivesheet can be decreased so that the efficiency of the inspecting work canbe enhanced.

EFFECT OF THE INVENTION

According to the apparatus for inspecting a circuit board and the methodof inspecting a circuit board in accordance with the present invention,it is possible to electrically inspect a circuit board with a highreliability even if a circuit board to be inspected which is aninspecting target has a minute electrode arranged at a fine pitch.

According to the apparatus for inspecting a circuit board and the methodof inspecting a circuit board in accordance with the present invention,it is possible to have an excellent follow-up for a height with respectto a variation in the height of an electrode to be inspected in acircuit board to be inspected which is an inspecting target and toexecute an accurate inspection without generating a defectiveconduction.

According to the apparatus for inspecting a circuit board and the methodof inspecting a circuit board in accordance with the present invention,the concentration of a stress in the inspection for the anisotropicallyconductive sheet can be dispersed well and a durability to a repetitiveuse can be enhanced.

According to the apparatus for inspecting a circuit board in accordancewith the present invention, it is possible to lessen a work forproviding a through hole on an insulating plate to hold the conductivepin through a drill processing, thereby reducing a cost.

According to the apparatus for inspecting a circuit board and the methodof inspecting a circuit board in accordance with the present invention,there is employed the structure in which the anisotropically conductiveelastomer sheet of a dispersion type is disposed on both sides of therelay board. By reducing the thickness of the anisotropically conductiveelastomer sheet of a dispersion type to be disposed, therefore, it ispossible to inspect the circuit board to be inspected with a highresolution and to well absorb a step caused by a variation in the heightof the electrode to be inspected in the circuit board to be inspected,and furthermore, to obtain a high durability to a repetitive use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view for explaining an embodiment of an inspectingapparatus according to the present invention.

FIG. 2 is a sectional view showing a lamination state in the inspectionand use of the inspecting apparatus illustrated in FIG. 1.

FIG. 3 is a view showing a surface on a circuit board side of a boardfor pitch conversion.

FIG. 4 is a view showing a surface on the pin side of the board forpitch conversion.

FIG. 5( a) is a partial sectional view showing a relay board and FIG. 5(b) is a partial top view showing the relay board.

FIG. 6 is a sectional view for explaining a process for manufacturingthe relay board.

FIG. 7 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 8 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 9 is a partially sectional view showing the first anisotropicallyconductive sheet.

FIG. 10 is a partially sectional view showing a state in which the boardfor pitch conversion, the relay board and a circuit board to beinspected are laminated through a first anisotropically conductivesheet.

FIG. 11 is a partially sectional view showing a second anisotropicallyconductive sheet.

FIG. 12 is a sectional view showing another example of the relay board.

FIG. 13 is an enlarged view showing a rigid conductor electrode in arelay board illustrated in FIG. 12.

FIG. 14 is a sectional view for explaining a process for manufacturingthe relay board.

FIG. 15 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 16 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 17 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 18 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 19 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 20 is a sectional view for explaining the process for manufacturingthe relay board.

FIG. 21 is a sectional view showing a state in which a firstanisotropically conductive sheet is laminated on both sides of the relayboard in FIG. 12.

FIG. 22 is a partially enlarged view showing the same.

FIG. 23 is a sectional view showing a state in which the relay board andthe first anisotropically conductive sheet in FIG. 21 are laminated on aboard for pitch conversion.

FIG. 24 is a sectional view showing a relay pin unit.

FIG. 25 is a sectional view showing apart of a conductive pin, anintermediate holding plate and an insulating plate in the relay pinunit.

FIG. 26 is the same sectional view as FIG. 25, illustrating anotherexample of the structure of the relay pin unit.

FIG. 27 is a sectional view showing a process to be carried out beforethe conductive pin is disposed between a first insulating plate and asecond insulating plate in the structure of FIG. 26.

FIG. 28 is a sectional view showing the relay pin unit having a bendingand holding plate disposed therein.

FIG. 29 is a partially enlarged view showing an intermediate holdingplate projecting surface which is projected in a direction of athickness of the intermediate holding plate of the relay pin unit.

FIG. 30 is a partially enlarged sectional view for explaining anembodiment of the inspecting apparatus according to the presentinvention.

FIG. 31 is a partially enlarged sectional view for explaining the stateof the use of the inspecting apparatus according to an embodiment of thepresent invention.

FIG. 32 is a partially enlarged sectional view for explaining the stateof the use of the relay pin unit in the inspecting apparatus accordingto the present invention.

FIG. 33 is a partially enlarged sectional view for explaining the stateof the use of the inspecting apparatus according to the embodiment ofthe present invention.

FIG. 34 is the same sectional view as FIG. 30, illustrating anotherembodiment of the inspecting apparatus according to the presentinvention.

FIG. 35 is an enlarged sectional view showing a relay pin unit in FIG.34.

FIG. 36 is a sectional view showing a conventional apparatus forinspecting a circuit board.

EXPLANATION OF DESIGNATIONS

-   -   1 circuit board to be inspected    -   2 electrode to be inspected    -   3 electrode to be inspected    -   11 a first inspecting jig    -   11 b second inspecting jig    -   21 a, 21 b circuit board side connector    -   22 a, 22 b first anisotropically conductive sheet    -   23 a, 23 b board for pitch conversion    -   24 a, 24 b terminal electrode    -   25 a, 25 b connecting electrode    -   26 a, 26 b second anisotropically conductive sheet    -   27 terminal electrode for current    -   28 terminal electrode for voltage    -   29 a, b relay board    -   31 a, 31 b relay pin unit    -   32 a, 32 b conductive pin    -   33 a, 33 b first support pin    -   34 a, 34 b first insulating plate    -   35 a, 35 b second insulating plate    -   36 a, 36 b intermediate holding plate    -   37 a, 37 b second support pin    -   38A first abutment support position    -   38B second abutment support position    -   39 holding plate support pin    -   39A abutment support position    -   41 a, 41 b tester side connector    -   42 a, 42 b third anisotropically conductive sheet    -   43 a, 43 b connector board    -   44 a, 44 b tester side electrode    -   45 a, 45 b pin side electrode    -   46 a, 46 b base plate    -   49 a, 49 b support pin    -   51 insulating board    -   52 wiring    -   53 internal wiring    -   54 insulating layer    -   55 insulating layer    -   61 sheet base material    -   62 conductive particle    -   63 through hole    -   64 through hole    -   65 plated layer    -   66 resist layer    -   71 insulating portion    -   72 conductive path forming portion    -   73 protruded portion    -   75 rigid conductor electrode    -   75 a protruded portion    -   76 insulating portion    -   77 board    -   81 a, 81 b end portion    -   82 central portion    -   83, 83 a, 83 b through hole    -   84 bending and holding plate    -   85 through hole    -   86 through hole    -   90A laminating material    -   90B composite laminating material    -   91 insulating board    -   91H through hole    -   92 rigid conductor electrode    -   92 a drum portion    -   92 b terminal portion    -   93A metal layer    -   93B metallic thin layer    -   93K opening    -   94 resist film    -   94H pattern hole    -   101 circuit board to be inspected    -   102 electrode to be inspected    -   103 electrode to be inspected    -   111 a first inspecting jig    -   111 b second inspecting jig    -   121 a, 121 b circuit board side connector    -   122 a, 122 b first anisotropically conductive sheet    -   123 a, 123 b board for pitch conversion    -   124 a, 124 b terminal electrode    -   125 a, 125 b connecting electrode    -   126 a, 126 b second anisotropically conductive sheet    -   131 a, 131 b relay pin unit    -   132 a, 132 b conductive pin    -   133 a, 133 b support pin    -   134 a, 134 b insulating plate    -   141 a, 141 b tester side connector    -   142 a, 142 b third anisotropically conductive sheet    -   143 a, 143 b connector board    -   144 a, 144 b tester side electrode    -   145 a, 145 b pin side electrode    -   146 a, 146 b base plate    -   A intermediate holding plate projecting surface    -   L1 distance    -   L2 distance    -   Q1 diagonal line    -   Q2 diagonal line    -   R1 unit lattice region    -   R2 unit lattice region

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to the drawings. In the following description, in some casesin which a pair of identical components in a first inspecting jig and asecond inspecting jig (for example, a circuit board side connector 21 aand a circuit board side connector 21 b, a first anisotropicallyconductive sheet 22 a and a first anisotropically conductive sheet 22 b,and the like) are generally referred, symbols “a” and “b” are omitted(for example, the first anisotropically conductive sheet 22 a and thefirst anisotropically conductive sheet 22 b are generally referred to asa “first anisotropically conductive sheet 22”).

FIG. 1 is a sectional view for explaining an embodiment of an inspectingapparatus according to the present invention, and FIG. 2 is a sectionalview showing a lamination state in a use for an inspection of theinspecting apparatus in FIG. 1.

The inspecting apparatus serves to carry out an electrical inspectionfor a circuit board to be inspected by measuring an electricalresistance between electrodes to be inspected in a circuit board 1 to beinspected which is an inspecting target, for example, a printed circuitboard for mounting an integrated circuit or the like.

In the inspecting apparatus, a first inspecting jig 11 a to be providedon an upper surface side and a second inspecting jig 11 b to be providedon a lower surface side in the circuit board 1 to be inspected aredisposed to be vertically opposed to each other as shown in FIGS. 1 and2.

The first inspecting jig 11 a comprises a circuit board side connector21 a including a relay board 29 a having a pair of first anisotropicallyconductive sheets (anisotropically conductive sheets of a dispersiontype) 22 a disposed on both sides thereof, a board 23 a for pitchconversion which is disposed on a reverse side to the circuit board 1 tobe inspected, and a second anisotropically conductive sheet (ananisotropically conductive sheet of an uneven distribution type) 26 awhich is disposed on the other surface side of the board 23 a for pitchconversion. Moreover, the first inspecting jig 11 a includes a relay pinunit 31 a. Furthermore, the first inspecting jig 11 a comprises a testerside connector 41 a including a connector board 43 a having a thirdanisotropically conductive sheet 42 a disposed on the relay pin unit 31a side, and a base plate 46 a.

The second inspecting jig 11 b also has the same structure as the firstinspecting jig 11 a and comprises a circuit board side connector 21 b, arelay pin unit 31 b and a tester side connector 41 b.

An electrode 2 to be inspected is formed on an upper surface of thecircuit board 1 to be inspected and an electrode 3 to be inspected isalso formed on a lower surface thereof, and these are electricallyconnected to each other.

FIG. 3 is a view showing a surface on the side of the circuit board 1 tobe inspected in the board 23 for pitch conversion, FIG. 4 is a viewshowing a surface on the side of the relay pin unit 31, and FIG. 10 is apartially sectional view showing a state in which the board 23 for pitchconversion, the relay board 29 and the circuit board 1 to be inspectedare laminated through the first anisotropically conductive sheet 22.

A plurality of connecting electrodes (inspection electrodes) 25 to beelectrically connected to the electrodes 2 and 3 of the circuit board 1to be inspected is formed on one of the surfaces of the board 23 forpitch conversion, that is, the side of the circuit board 1 to beinspected as shown in FIG. 3. These connecting electrodes 25 aredisposed to correspond to the patterns of the electrodes 2 and 3 to beinspected in the circuit board 1 to be inspected.

Moreover, the connecting electrode 25 is constituted by a terminalelectrode 27 for a current and a terminal electrode 28 for a voltagewhich make a pair and are separated from each other, and are to beconnected to one electrode 2 to be inspected (one electrode 3 to beinspected) in the circuit board 1 to be inspected as shown in FIG. 3.

On the other hand, a plurality of terminal electrodes 24 to beelectrically connected to a conductive pin 32 of the relay pin unit 31is formed on the other surface of the board 23 for pitch conversion,that is, the opposite side of the circuit board 1 to be inspected asshown in FIG. 4. These terminal electrodes 24 are provided on latticepoints at a certain pitch of 2.54 mm, 1.8 mm, 1.27 mm, 1.06 mm, 0.8 mm,0.75 mm, 0.5 mm, 0.45 mm, 0.3 mm or 0.2 mm, for example, and the pitchis equal to the arrangement pitch of conductive pins 32 a and 32 b ofthe relay pin unit.

As shown in FIG. 10, the respective connecting electrodes 25 in FIG. 3are electrically connected to the corresponding terminal electrodes 24in FIG. 4 through a wiring 52 in FIG. 3 and an internal wiring 53 inFIG. 10 which penetrates in the direction of the thickness of aninsulating board 51.

An insulating portion provided on the surface of the board 23 for pitchconversion is constituted by an insulating layer 54 on which therespective connecting electrodes 25 are formed to be exposed to thesurface of the insulating board, for example. The thickness of theinsulating layer 54 is preferably 5 to 100 μm and is more preferably 10to 60 μm. In some cases in which the thickness is excessively great, itis hard to carry out the electrical connection of the connectingelectrode 25 to the anisotropically conductive sheet.

As a material for forming the insulating board of the board for pitchconversion, it is possible to generally use a material to be utilized asthe base material of a printed circuit board. More specifically,examples of the material can include a polyimide resin, a glass fiberreinforced polyimide resin, a glass fiber reinforced epoxy resin, aglass fiber reinforced bismaleimide triazine resin and the like.

As a material for forming the insulating layers 54 and 55, it ispossible to use a polymer material which can be molded like a thin film.Specific examples can include an epoxy resin, an acylic resin, a phenolresin, a polyimide resin, a polyamide resin, these mixtures, a resistmaterial and the like.

The board 23 for pitch conversion can be manufactured in the followingmanner, for example. First of all, a laminating material having ametallic thin layer laminated on both sides of a plate-shaped insulatingboard is prepared and a plurality of through holes penetrating in thedirection of the thickness of the laminating material is formed for thelaminating material corresponding to a pattern corresponding to aterminal electrode to be formed by a numerical control type drillingdevice, a photoetching treatment, a laser processing treatment or thelike.

Subsequently, the inner part of the through hole formed on thelaminating material is subjected to nonelectrolytic plating andelectrolytic plating so that a via hole coupled to the metallic thinlayer on both sides of the board is formed. Then, the metallic thinlayer is subjected to the photoetching treatment so that a wiringpattern and a connecting electrode are formed on the surface of theinsulating board, and furthermore, a terminal electrode is formed on asurface at an opposite side.

Then, the insulating layer 54 is formed on the surface of the insulatingboard 51 in such a manner that the respective connecting electrodes 25are exposed, and furthermore, the insulating layer 55 is formed on asurface at an opposite side thereof in such a manner that the respectiveterminal electrodes 24 are exposed. Consequently, the board 23 for pitchconversion is obtained. The thickness of the insulating layer 55 ispreferably 5 to 100 μm and is more preferably 10 to 60 μm.

FIG. 5( a) is a sectional view showing the relay board, FIG. 5( b) is apartial top view showing the same and FIG. 8( c) is an enlargedsectional view showing the relay board. A board 77 of the relay board 29is provided with a large number of through holes in which a rigidconductor electrode 75 is to be disposed in accordance with theelectrode pattern of the board 23 for pitch conversion. A polymericelastic body is buried in the through hole so that an insulating portion76 is formed, and the rigid conductor electrode 75 is formed in apenetration so as to be surrounded by the insulating portion 76.

For example, a pair of rigid conductor electrodes 75 corresponding tothe terminal electrode 27 for a current and the terminal electrode 28for a voltage in FIG. 3 which are used in a 4-terminal inspection aredisposed in each of the large number of through holes formed on theboard 77. Although the number of the rigid conductor electrodes 75 to bedisposed in one through hole is not particularly restricted, it ispreferably one to four. Corresponding to the connecting electrode of theboard 23 for pitch conversion, the number of the rigid conductorelectrodes 75 may be varied every through hole of the board 77.

As shown in FIG. 8( c), it is preferable that a protruded portion 75 aprotruded from the surface of the insulating portion 76 should be formedon both end sides of the rigid conductor electrode 75. Thus, theprotruded portion 75 a is formed so that the electrode to be inspectedin the circuit board 1 to be inspected and the connecting electrode ofthe board 23 for pitch conversion can be conducted reliably with a smallresistance value.

The insulating portion 76 can be formed by an elastic polymer substancehaving across-linking structure. Specific examples of a curing polymersubstance forming material which can be used for obtaining such elasticpolymer substances include conjugated diene rubber such as polybutadienerubber, natural rubber, polyisoprene rubber, styrene-butadiene copolymerrubber or acrylonitrile-butadiene copolymer rubber, and hydrogenatedproducts thereof; block copolymer rubber such as styrene-butadiene-dieneblock terpolymer rubber or styrene-isoprene block copolymer, andhydrogenated products thereof; and chloroprene, urethane rubber,polyester type rubber, epichlorohydrin rubber, silicone rubber,ethylene-propylene copolymer rubber and ethylene-propylene-dieneterpolymer rubber, and the like.

In the foregoing, in the case in which a weather resistance is required,it is preferable to use a material other than the conjugated dienerubber, and particularly, to use the silicone rubber from the viewpointof the molding and processing properties and the electricalcharacteristics.

For the silicone rubber, liquid silicone rubber is preferablycrosslinked or condensed. The liquid silicone rubber having a viscosityof 10⁵ poises or less at a shear proportion of 10⁻¹ sec is preferablyused and may be any of a condensation type, an addition type and thosecontaining a vinyl group or a hydroxyl group and the like. Specificexamples can include dimethyl silicone raw rubber, methylvinyl siliconeraw rubber and methylphenylvinyl silicone raw rubber, and the like.

Moreover, it is preferable that the silicone rubber should have amolecular weight Mw (which indicates a weight-average molecular weightdetermined in terms of standard polystyrene and the following is thesame) of 10,000 to 40,000. Moreover, it is preferable that a molecularweight distribution index (which indicates a value of a ratio Mw/Mn of aweight-average molecular weight Mw determined in terms of standardpolystyrene to a number-average molecular weight Mn determined in termsof standard polystyrene and the following is the same) should be equalto or smaller than 2 because an excellent heat resistance can beobtained.

Specific examples of a material for the board 77 in the relay boardinclude a mesh, a nonwoven fabric, a metallic mesh and the like whichare formed by a composite resin material such as a glass fiberreinforced polyimide resin, a glass fiber reinforced epoxy resin or aglass fiber reinforced bismaleimide triazine resin, a resin materialhaving a high mechanical strength such as a polyimide resin, a polyesterresin, a polyaramid resin, a polyamide resin, a bismaleimide triazineresin or a liquid crystal polymer, a metallic material such asstainless, and an organic fiber such as a fluororesin fiber, an aramidfiber, a polyethylene fiber, a polyallylate fiber, a nylon fiber, apolyester fiber or a liquid crystal polymer fiber. The thickness of theboard 77 depends on the forming material, and is preferably 20 to 500μm.

A method of manufacturing the relay board 29 will be specificallydescribed below. First of all, as shown in FIG. 6( a), the plate-shapedboard 77 is prepared. For the board 77, a through hole 63 is formed asshown in FIG. 6( b) in a position in which the rigid conductor electrode75 is to be disposed by a numerical control type drilling device, aphotoetching treatment, a laser processing treatment, a punch processingor the like, for example.

Subsequently, an inside of the through hole 63 is coated with a materialfor an insulating portion by using a printing method such as screenprinting, a roll coating method, a blade coating method or the like, forexample, and a curing treatment is thus carried out. As shown in FIG. 6(c), consequently, the insulating portion 76 formed of a polymericelastic body is formed over the whole inside of the through hole 63. Thecuring treatment of the material for an insulating portion is usuallycarried out by a heating treatment. A specific heating temperature and aspecific time required for heating are properly set in consideration ofthe type of the material for an insulating portion or the like.

As shown in FIG. 7( a), then, a through hole 64 for forming the rigidconductor electrode 75 is provided on the insulating portion 76. Thethrough hole 64 can be formed in the following manner. First of all, ametallic thin layer for a plated electrode is formed of copper, gold,aluminum, rhodium or the like over a surface on one surface side of theboard 77 by using a nonelectrolytic plating method, a sputtering methodor the like.

A resist layer having a plurality of openings formed thereon inaccordance with a specific pattern corresponding to a forming pattern ofthe through hole 64 is provided on the metallic thin layer by aphotolithographic technique and an electrolytic plating treatment isthen carried out by setting the metallic thin layer to be the platedelectrode, thereby forming a metal mask such as copper, iron, aluminum,gold, rhodium or the like in the openings of the resist layer.

Next, a laser processing is carried out over the resist layer, themetallic thin layer and the insulating portion 76 by using a carbondioxide layer or the like, thereby forming a through hole to penetratethrough the resist layer, the metallic thin layer and the insulatingportion 76. Thereafter, the metallic thin layer and the metal mask whichremain are removed from the surface of the insulating portion 76 so thatthe board in FIG. 7( a) in which the through hole 64 is formed on theinsulating portion 76 is obtained.

The board 77 in FIG. 7( a) thus obtained is subjected to nonelectrolyticplating using copper over a whole surface thereof. Consequently, acopper plated layer 65 for electrolytic plating is formed as shown inFIG. 7( b).

As shown in FIG. 7( c), subsequently, a resist layer 66 provided with anopening in a position of the through hole 64 is formed on surfaces atboth sides of the board 77 by the photolithographic technique. Athickness of the resist layer 66 is set corresponding to a protrusionwidth from the insulating portion 76 in the rigid conductor electrode 65to be formed.

After the resist layer 66 is formed, electrolytic copper plating(through hole plating) is carried out by setting the copper plated layer65 to be a common electrode, thereby forming the rigid conductorelectrode 75 on each through hole 64 as shown in FIG. 8( a).

Subsequently, the resist layer 66 is removed as shown in FIG. 8( b).Then, etching is carried out with acid for a short time to leave theprotruded portions on both end sides of the rigid conductor electrode75, thereby cleaning and removing the plated layer 65 selectively.Consequently, the relay board 29 shown in FIG. 8( c) is obtained.

In the first anisotropically conductive sheet 22 constituting thecircuit board side connector 21 and disposed on both sides of the relayboard 29, a large number of conductive particles 62 are contained in thesheet base material 61 formed by an insulating elastic polymer in astate in which they are dispersed in a planar direction and are arrangedin the direction of a thickness as shown in FIG. 9.

The thickness of the first anisotropically conductive sheet 22 ispreferably 20 to 200 μm and is more preferably 30 to 100 μm. In somecases in which a minimum thickness is smaller than 20 μm, the mechanicalstrength of the first anisotropically conductive sheet 22 is easilyreduced so that a necessary durability cannot be obtained. On the otherhand, in the case in which the thickness of the first anisotropicallyconductive sheet 22 is greater than 200 μm, a predetermined insulatingproperty cannot be obtained between conductive paths formed by apressurization so that an electrical short circuit is caused between theelectrodes to be inspected and it is hard to electrically inspect thecircuit board to be inspected when a pitch of the electrodes to beconnected is small.

The elastic polymer substance constituting the sheet base material 61 ofthe first anisotropically conductive sheet 22 has a durometer hardnesswhich is preferably 30 to 90, is more preferably 35 to 80 and is furtherpreferably 40 to 70. In this specification, the “durometer hardness”indicates a measurement by a type A durometer based on a durometerhardness test of JIS K6253. In the case in which the durometer hardnessof the elastic polymer substance is smaller than 30, the anisotropicallyconductive sheet is greatly compressed and deformed so that a greatpermanent set is generated in the pressing in the direction of thethickness. For this reason, the anisotropically conductive sheet isdeteriorated in an early stage so that it is hard to carry out a use foran inspection. Consequently, a durability is apt to be reduced.

On the other hand, in the case in which the durometer hardness of theelastic polymer substance is greater than 90, the amount of adeformation in the direction of the thickness becomes insufficient whenthe anisotropically conductive sheet is pressed in the direction of thethickness. For this reason, an excellent connecting reliability cannotbe obtained so that a connecting failure is generated easily.

Although an elastic polymer substance constituting the base material ofthe first anisotropically conductive sheet 22 which exhibits thedurometer hardness is not particularly restricted, it is preferable touse silicone rubber in respect of forming and processing properties andelectrical characteristics.

It is preferable that a ratio W₁/D₁ of a thickness W₁ (μm) of the firstanisotropically conductive sheet 22 to a number-average particlediameter D₁ (μm) of the magnetically conductive particle should be 1.1to 10. Herein, the “number-average particle diameter of the magneticallyconductive particle” implies a measurement carried out by a laserdiffracting and scattering method. In the case in which the ratio W₁/D₁is lower than 1.1, the diameter of the magnetically conductive particleis equal to or greater than the thickness of the anisotropicallyconductive sheet. Therefore, the elasticity of the anisotropicallyconductive sheet is reduced. When the anisotropically conductive sheetis disposed between an object to be inspected (the circuit board 1 to beinspected) such as a printed wiring board and the inspection electrodeto carry out a pressurization, thereby achieving a contact conductionstate, therefore, the object to be inspected is apt to be damaged.

On the other hand, in the case in which the ratio W₁/D₁ is higher than10, a large number of conductive particles are arranged between theobject to be inspected and the inspection electrode to form a chain andthe contacts of the conductive particles are present when theanisotropically conductive sheet is disposed between the object to beinspected such as the printed wiring board and the inspection electrodeto carry out the pressurization, thereby achieving the contactconduction state. Therefore, an electrical resistance value is increasedeasily and a use for the electrical inspection is apt to be hard.

For a magnetically conductive particle, a saturation magnetization ispreferably equal to or greater than 0.1 Wb/m², is more preferably equalto or greater than 0.3 Wb/m², and is particularly preferably equal to orgreater than 0.5 Wb/m² in that the magnetically conductive particle caneasily be moved by the action of the magnetic field in the sheet moldingmaterial for forming the anisotropically conductive sheet.

Since the saturation magnetization is equal to or greater than 0.1Wb/m², the magnetically conductive particle can reliably be moved by theaction of the magnetic field in a manufacturing process thereof to bringa desirable orientation state. Therefore, it is possible to form thechain of the magnetically conductive particle when using theanisotropically conductive sheet.

Specific examples of the magnetically conductive particle include theparticle of a metal exhibiting a magnetism such as iron, nickel orcobalt, the particle of their alloy, a particle containing these metals,a composite particle obtained by setting these particles to be coreparticles and coating the surfaces of the core particles with a highlyconductive metal, a non-magnetic metal particle, the particle of aninorganic substance such as glass beads, a composite particle obtainedby setting a polymer particle to be a core particle and plating thesurface of the core particle with a highly conductive metal, a compositeparticle obtained by coating the core particle with both a conductivelymagnetic material and a highly conductive metal such as ferrite or anintermetallic compound, and the like.

The “highly conductive metal” implies a metal having an electricconductivity of 5×10⁶Ω⁻¹m⁻¹ or more at 0° C. For such a highlyconductive metal, specifically, it is possible to use gold, silver,rhodium, platinum, chromium or the like. Among them, it is preferablethat the gold should be used in that it is chemically stable and has ahigh electric conductivity.

In the magnetically conductive particles, it is preferable to use acomposite particle obtained by setting a nickel particle to be a coreparticle and plating a surface thereof with a highly conductive metalsuch as gold or silver.

As means for coating the surface of the core particle with the highlyconductive metal, it is possible to use a nonelectrolytic platingmethod, for example.

For the magnetically conductive particle, the coefficient of a varianceof a number-average particle diameter is preferably equal to or smallerthan 50%, is more preferably equal to or smaller than 40%, is furtherpreferably equal to or smaller than 30%, and is particularly preferablyequal to or smaller than 20%. The “coefficient of variance of thenumber-average particle diameter” is calculated by an equation of(σ/Dn)×100 (σ represents a value of a standard deviation of the particlediameter and Dn represents a number-average particle diameter of theparticle).

Since the number-average particle diameter of the magneticallyconductive particle has a coefficient of variance of 50% or less, thedegree of the inequality of the particle diameter is reduced.Consequently, it is possible to reduce a partial variation in aconductiveness in the anisotropically conductive sheet which isobtained.

Such a magnetically conductive particle can be obtained by changing ametallic material into a particle in the usual way or preparing ametallic particle put on the market and carrying out a classificationtreatment over the particle. The classification treatment for theparticle can be performed by means of a classifying device such as anair classifying device or a sonic sieving device. The specificconditions of the classifying treatment are properly set correspondingto the number-average particle diameter of a conductive metallicparticle which is intended, the type of the classifying device and thelike.

Although the specific shape of the magnetically conductive particle isnot particularly restricted, a secondary particle having a plurality ofspherical primary particles coupled integrally is used preferably, forexample.

In the case in which a composite particle (hereinafter referred to as a“conductive composite metal particle”) having a surface of a coreparticle coated with a highly conductive metal is used as themagnetically conductive particle, the coating rate of the highlyconductive metal on the surface of the conductive composite metalparticle (the ratio of the coating area of the highly conductive metalto the surface area of the core particle) is preferably equal to orhigher than 40%, is further preferably equal to or higher than 45%, andis particularly preferably 47 to 95% in that an excellent conductivenesscan be obtained.

Moreover, the amount of coating of the highly conductive metal ispreferably 2.5 to 50% by weight with respect to the weight of the coreparticle, is more preferably 3 to 45% by weight, is further preferably3.5 to 40% by weight, and is particularly preferably 5 to 30% by weight.

The anisotropically conductive sheet containing a large number ofconductive particles 62 dispersed in a planar direction and arranged inthe direction of a thickness in the insulating elastic polymer substancecan be manufactured by a method of preparing a molding material having afluidity which contains a conductive particle exhibiting a magnetism ina material for a polymer substance to be changed into an elastic polymersubstance through curing, forming a molding material layer constitutedby the molding material between a molding member on one surface sideprovided in contact with one surface in the molding material layer and amolding member on the other surface side provided in contact with theother surface in the molding material layer, and causing a magneticfield to act in the direction of the thickness for the molding materiallayer, and furthermore, carrying out a curing treatment over the moldingmaterial layer as disclosed in Japanese Laid-Open Patent Publication No.2003-77560, for example.

FIG. 10 is a partially sectional view showing a state in which a boardfor pitch conversion, a relay board and a circuit board to be inspectedare laminated through a first anisotropically conductive sheet. FIG. 10shows an example of the case in which a 4-terminal inspection is carriedout. As shown, the relay board 29 is disposed through the firstanisotropically conductive sheet 22 between the circuit board 1 to beinspected and the board 23 for pitch conversion, and a pair of rigidconductor electrodes 75 and 75 are formed in one through hole of therelay board 29 corresponding to the terminal electrode 27 for a currentand the terminal electrode 28 for a voltage in the board 23 for pitchconversion. The terminal electrode 27 for a current and the terminalelectrode 28 for a voltage and the pair of rigid conductor electrodes 75and 75 are electrically connected to each other through the firstanisotropically conductive sheet 27. On the other hand, the electrode 2to be inspected in the circuit board 1 to be inspected and the pair ofrigid conductor electrodes 75 and 75 are electrically connected throughthe first anisotropically conductive sheet 22, and the electricalinspection is carried out in this state.

A second anisotropically conductive sheet 26 provided on the relay pinunit 31 side of the board 23 for pitch conversion is constituted by aconductive path forming portion 72 formed by arranging a large number ofconductive particles 62 in the direction of a thickness in an insulatingelastic polymer material and an insulating portion 71 for separating therespective conductive path forming portions 72 as shown in FIG. 11.Thus, the conductive particle 62 is dispersed nonuniformly in the planardirection in only the conductive path forming portion 72.

A thickness W₂ of the conductive path forming portion 72 is preferably0.1 to 2 mm and is more preferably 0.2 to 1.5 mm. In the case in whichthe thickness W₂ is smaller than 0.1 mm, an absorption power for thepressurization in the direction of a thickness is low and the absorptionof a pressurizing force by an inspecting jig is reduced in an inspectionso that the effect of relieving a shock on the circuit board sideconnector 21 is decreased. For this reason, a deterioration in the firstanisotropically conductive sheet 22 is suppressed with difficulty. As aresult, the number of exchanges of the first anisotropically conductivesheet 22 in the repetitive inspection of the circuit board 1 to beinspected is increased so that an inspection efficiency is reduced. Onthe other hand, in some cases in which the thickness W₂ is greater than2 mm, an electrical resistance in the direction of a thickness is easilyincreased so that it is hard to carry out the electrical inspection.

It is preferable that the thickness of the insulating portion 71 shouldbe substantially equal to or smaller than that of the conductive pathforming portion 72. As shown in FIG. 11, the thickness of the insulatingportion 71 is set to be smaller than that of the conductive path formingportion 72, and the conductive path forming portion 72 forms a protrudedportion 73 which is protruded from the insulating portion 71.Consequently, the conductive path forming portion 72 is easily deformedagainst the pressurization in the direction of the thickness and theabsorption power for the pressurizing force is increased. Consequently,the pressurizing force of the inspecting jig is absorbed in theinspection so that the shock on the circuit board side connector 21 canbe relieved.

In the case in which the magnetically conductive particle is used forthe conductive particle 62 constituting the second anisotropicallyconductive sheet 26, a number-average particle diameter is preferably 5to 200 μm, is more preferably 5 to 150 μm, and is further preferably 10to 100 μm. The “number-average particle diameter of the magneticallyconductive particle” is measured by a laser diffracting and scatteringmethod. When the number-average particle diameter of the magneticallyconductive particle is equal to or larger than 5 μm, the conductive pathforming portion of the anisotropically conductive sheet can easily bepressurized and deformed. In the case in which the magneticallyconductive particle is oriented by a magnetic field orientationtreatment in the manufacturing process, moreover, the magneticallyconductive particle can easily be oriented. When the number-averageparticle diameter of the magnetically conductive particle is equal to orsmaller than 200 μm, the elasticity of the conductive path formingportion 72 of the anisotropically conductive sheet can be enhanced sothat the pressurization and deformation can easily be carried out.

It is preferable that a ratio W₂/D₂ of the thickness W₂ (μm) of theconductive path forming portion 72 to a number-average particle diameterD₂ (μm) of the magnetically conductive particle should be 1.1 to 10. Inthe case in which the ratio W₂/D₂ is smaller than 1.1, the diameter ofthe magnetically conductive particle is equal to or larger than thethickness of the conductive path forming portion 72. Therefore, theelasticity of the conductive path forming portion 72 is lowered so thatthe absorption power for the pressurizing force in the direction of thethickness is reduced. For this reason, a capability for absorbing thepressurizing force of the inspecting jig in the inspection isdeteriorated so that the effect of relieving the shock on the circuitboard side connector 21 is decreased. Therefore, a deterioration in thefirst anisotropically conductive sheet 22 is suppressed with difficulty.As a result, the number of exchanges of the first anisotropicallyconductive sheet 22 is increased so that the inspection efficiency iseasily reduced in the repetitive inspection for the circuit board 1 tobe inspected.

On the other hand, in the case in which the ratio W₂/D₂ is greater than10, a large number of conductive particles are arranged to form a chainin the conductive path forming portion 72 so that a large number ofcontacts of the conductive particles are present. Consequently, anelectrical resistance value is easily increased.

Referring to an elastic polymer to be the base material of theconductive path forming portion 72, a durometer hardness measured by atype A durometer is preferably 15 to 60, is more preferably 20 to 50,and is further preferably 25 to 45.

In the case in which the durometer hardness of the elastic polymer issmaller than 15, the compression and deformation of the sheet in thepressing in the direction of the thickness is increased so that a greatpermanent set is generated. Consequently, the shape of the sheet isdeformed in an early stage so that an electrical connection in theinspection is easily hard to perform. In the case in which the durometerhardness of the elastic polymer is greater than 60, the deformation inthe pressing in the direction of the thickness is reduced. Consequently,the absorption power for the pressurizing force in the direction of thethickness is reduced. For this reason, a deterioration in the firstanisotropically conductive sheet 22 is suppressed with difficulty. As aresult, the number of exchanges of the first anisotropically conductivesheet 22 is increased so that the inspection efficiency is easilyreduced in the repetitive inspection for the circuit board 1 to beinspected.

While the elastic polymer to be the base material of the conductive pathforming portion 72 which exhibits the durometer hardness described aboveis not particularly restricted, it is preferable to use silicone rubberin respect of a processing property and an electrical characteristic.

The insulating portion 71 of the second anisotropically conductive sheet26 is formed by an insulating material which does not substantiallycontain a conductive particle. For the insulating material, it ispossible to use an insulating polymeric material, an inorganic material,a metallic material having a surface subjected to an insulatingtreatment or the like, for example. If the same material as the elasticpolymer used in the conductive path forming portion is utilized, aproduction can easily be carried out. In the case in which the elasticpolymer is used as the material of the insulating portion, it ispreferable that the elastic polymer having the durometer hardness withinthe range described above should be utilized.

As the magnetically conductive particle, it is possible to use theconductive particle to be utilized in the first anisotropicallyconductive sheet described above.

The second anisotropically conductive sheet 26 can be manufactured bythe following method, for example. First of all, there is prepared ametal mold for molding an anisotropically conductive sheet having such astructure that each whole shape is an almost plate and is constituted byan upper mold and a lower mold which correspond to each other, and amaterial layer filled in a molding space between the upper mold and thelower mold can be heated and cured while causing a magnetic field to acton the material layer.

In the metal mold for molding an anisotropically conductive sheet, thereis used a board having a mosaic-shaped layer in which a ferromagneticportion formed of iron or nickel for generating an intensitydistribution on a magnetic field in the metal mold and a non-magneticportion formed of a non-magnetic metal, for example, copper or a resinare provided alternately to be adjacent to each other in order to causea magnetic field to act on a material layer to form a conductive portionin a proper position. The ferromagnetic portion is arrangedcorresponding to the pattern of the conductive path forming portion tobe formed. The molding surface of the upper mold is flat and that of thelower mold has slight concavo-convex portions corresponding to theconductive path forming portion of the anisotropically conductive sheetto be formed.

A molding material containing a conductive particle exhibiting amagnetism in a polymer substance material to be changed into an elasticpolymer substance by curing is injected into the molding space of themetal mold for molding the anisotropically conductive sheet, therebyforming a molding material layer. Next, the ferromagnetic portion andthe non-magnetic portion in each of the upper and lower molds areutilized and a magnetic field having an intensity distribution in thedirection of a thickness thereof is caused to act on the moldingmaterial layer which is formed. Consequently, the conductive particlesare collected between the ferromagnetic portion in the upper mold andthe ferromagnetic portion in the lower mold positioned thereunder andare oriented to be arranged in the direction of a thickness. In thatstate, then, the molding material layer is subjected to a curingtreatment. Consequently, there is manufactured an anisotropicallyconductive sheet in which a plurality of columnar conductive pathforming portions is insulated from each other through an insulatingportion.

FIG. 12 is a sectional view showing another example of a relay board andFIG. 13 is an enlarged view showing a rigid conductor electrode in therelay board illustrated in FIG. 12. The relay board 29 includes aninsulating board 91 having a plurality of through holes 91H which isextended in the direction of a thickness respectively and is formed inaccordance with a pattern of an electrode to be inspected that is to beconnected, and a plurality of rigid conductor electrodes 92 disposed tobe protruded from both sides of the insulating board 91 in the throughholes 91H of the insulating board 91.

Each of the rigid conductor electrodes 92 is provided with a cylindricaldrum portion 92 a inserted in the through hole 91H of the insulatingboard 91 and a terminal portion 92 b coupled integrally with both endsof the drum portion 92 a. The terminal portion 92 b is exposed fromsurfaces on both sides of the insulating board 91.

A length L of the drum portion 92 a in the rigid conductor electrode 92is greater than a thickness d of the insulating board 91, and a diameterr2 of the drum portion 92 a is smaller than a diameter r1 of the throughhole 91H of the insulating board 91. On the other hand, a diameter r3 ofthe terminal portion 92 b in the rigid conductor electrode 92 is greaterthan a diameter of the through hole 91H of the insulating board 91.Consequently, the rigid conductor electrode 92 is held to be movable inthe direction of the thickness of the insulating board 91.

Specific examples of the material for the insulating board 91 caninclude a resin material such as a liquid crystal polymer, a polyimideresin, a polyester resin, a polyaramid resin or a polyamide resin, afiber reinforced resin material such as a glass fiber reinforced epoxyresin, a glass fiber reinforced polyester resin or a glass fiberreinforced polyimide resin, a composite resin material obtained bycontaining an inorganic material such as alumina or boron nitride as afiller in an epoxy resin, and others.

In the case in which the inspecting apparatus according to the presentinvention comprising the relay board 29 is used in a high-temperatureenvironment, the insulating board 91 to be used preferably has acoefficient of linear expansion of 3×10⁻⁵/K or less, more preferably1×10⁻⁶/K to 2×10⁻⁵/K and particularly preferably 1×10⁻⁶/K to 6×10⁻⁶/K.By using the insulating board 91 having the coefficient of linearexpansion within the range described above, it is possible to suppressthe positional shift of the rigid conductor electrode 92 due to thethermal expansion of the insulating board 91.

The thickness d of the insulating board 91 is preferably 10 to 200 μmand is more preferably 15 to 100 μm. The diameter r1 of the through hole91H of the insulating board 91 is preferably 20 to 250 μm and is morepreferably 30 to 150 μm.

For the material of the rigid conductor electrode 92, a metal materialhaving a rigidity is suitable. In the method of manufacturing the relayboard 29 which will be described below, particularly, it is preferableto use a material which is harder to etch than the metallic thin layerformed on the insulating board 91. Specific examples of such a metalmaterial can include a metallic single substance such as nickel, cobalt,gold or aluminum, these alloys and the like.

The diameter r2 of the drum portion 92 a in the rigid conductorelectrode 92 is preferably equal to or greater than 18 μm and is morepreferably equal to or greater than 25 μm. In some cases in which thediameter r2 is excessively small, a necessary strength for the rigidconductor 92 cannot be obtained.

A difference (r1−r2) between the diameter r1 of the through hole 91H ofthe insulating board 91 and the diameter r2 of the drum portion 92 a inthe rigid conductor electrode 92 is preferably equal to or larger than 1μm and is more preferably equal to or larger than 2 μm. In some cases inwhich the difference is excessively small, it is hard to move the rigidconductor electrode 92 in the direction of the thickness of theinsulating board 91.

It is preferable that the diameter r3 of the terminal portion 92 b inthe rigid conductor electrode 92 should be 70 to 150% of the diametersof the electrodes 2 and 3 to be inspected in the circuit board 1 to beinspected. A difference (r3-r1) between the diameter r3 of the terminalportion 92 b in the rigid conductor electrode 92 and the diameter r1 ofthe through hole 91H of the insulating board 91 is preferably equal toor larger than 5 μm and is more preferably equal to or larger than 10μm. In the case in which the difference is excessively small, there is apossibility that the rigid conductor electrode 92 might slip from theinsulating board 91.

A distance of the rigid conductor electrode 92 which can be moved in thedirection of the thickness of the insulating board 91, that is, adifference (L−d) between the length L of the drum portion 92 a in therigid conductor electrode 92 and the thickness d of the insulating board91 is preferably 5 to 50 μm and is more preferably 10 to 40 μm. In somecases in which the distance of the rigid conductor electrode 92 whichcan be moved is excessively small, the concavo-convex absorbing power ofthe electrodes 2 and 3 to be inspected is not sufficient. In the case inwhich the distance of the rigid conductor electrode 92 which can bemoved is excessively great, the length of the drum portion 92 a of therigid conductor electrode 92 which is exposed from the through hole 91Hof the insulating board 91 is increased. For this reason, there is apossibility that the drum portion 92 a might be buckled or damaged inthe inspection.

In the relay board 29 described above, the rigid conductor electrode 92is disposed in the through hole 91H of the insulating board 91 so as tobe movable in the direction of a thickness, and the rigid conductorelectrode 92 includes, at both ends of the drum portion 92 a, theterminal portion 92 b having a larger diameter than the through hole 91Hof the insulating board 91. For this reason, the terminal portion 92 bfunctions as a stopper and the rigid conductor electrode 92 can beprevented from slipping from the insulating board 91. Also in the casein which the relay board 29 is handled singly, accordingly, the handlingis easy.

The method of manufacturing the relay board will be descried below withreference to FIGS. 14 to 20. First of all, there is prepared alaminating material 90A in which a metal layer 93A having an easyetching property is laminated integrally with either side of theinsulating board 91 as shown in FIG. 14.

An etching treatment is carried out over the metal layer 93A in thelaminating material 90A and a part thereof is removed. Consequently, aplurality of openings 93K is formed in accordance with the patterns ofthe electrodes 2 and 3 to be inspected in the circuit board 1 to beinspected as shown in FIG. 15.

As shown in FIG. 16, next, the through holes 91H extended in thedirection of the thickness are formed on the insulating board 91 in thelaminating material 90A in a communication with the openings 93K of themetal layer 93A, respectively.

As shown in FIG. 17, then, a cylindrical metallic thin layer 93B havingthe easy etching property is formed so as to cover an internal wallsurface of the through hole 91H of the insulating board 91 and anopening edge of the metal layer 93A.

Thus, there is obtained a composite laminating material 90B comprisingthe insulating board 91 provided with the through holes 91H extended inthe direction of the thickness respectively, the metal layer 93A havingthe easy etching property which is laminated on either side of theinsulating board 91 and is provided with the openings 93K communicatingwith the through holes 91H of the insulating board 91, and the metallicthin layer 93B having the easy etching property which is formed to coverthe internal wall surface of the through hole 91H of the insulatingboard 91 and the opening edge of the metal layer 93A.

In the above manufacturing process, examples of a method of forming thethrough hole 91H of the insulating board 91 can include a laserprocessing method, a drill processing method, an etching processingmethod and the like.

Examples of the metal material having the easy etching property whichconstitute the metal layer 93A and the metallic thin layer 93B caninclude copper and the like.

A thickness of the metal layer 93A is set in consideration of anintended distance of the rigid conductor 92 which can be removed, and ispreferably 5 to 25 μm and is more preferably 8 to 20 μm.

A thickness of the metallic thin layer 93B is set in consideration ofthe diameter of the through hole 91H in the insulating board 91 and thediameter of the drum portion 92 a in the rigid conductor electrode 92 tobe formed.

Examples of a method of forming the metallic thin layer 93B can includea nonelectrolytic plating method and the like.

A photoplating treatment is carried out over the composite laminatingmaterial 90B obtained through the above manufacturing process so thatthe rigid conductor electrode 92 is formed in each of the through holes91H in the insulating board 91. More specifically, as shown in FIG. 18,the resist film 94 is formed on the surface of the metal layer 93Aprovided on either side of the insulating board 91 and the other surfaceof the insulating board 91, and a plurality of pattern holes 94Hcommunicating with the through holes 91H of the insulating board 91 arethen formed on the resist film 94 in accordance with the pattern of theterminal portion 92 b in the rigid conductor electrode 92 to be formed.

As shown in FIG. 19, next, a metal is deposited on the surface of themetallic thin layer 93B by using the metal layer 93A to be a commonelectrode. Consequently, a metal is filled in the through hole 91H ofthe insulating board 91 and the pattern hole 94H of the resist film 94,thereby forming the rigid conductor electrode 92 extended in thedirection of the thickness of the insulating board 91.

After the rigid conductor electrode 92 is thus formed, the resist film94 is removed from the surface of the metal layer 93A. As shown in FIG.20, consequently, the metal layer 93A is exposed. Thereafter, an etchingtreatment is carried out to remove the metal layer 93A and the metallicthin layer 93B. Thus, the relay board 29 shown in FIG. 12 is obtained.

According to the manufacturing method described above, the metal layer93A and the metallic thin layer 93B having the easy etching propertiesare previously formed on the either side of the insulating board 91 andthe internal wall surface of the through hole 91H, respectively.Subsequently, the rigid conductor electrode 92 is formed in the throughhole 91H of the insulating board 91 and the metal layer 93A and themetallic thin layer 93B are then removed by the etching treatment.Accordingly, a desirable gap is reliably formed between the insulatingboard 91 and the rigid conductor electrode 92. Therefore, the movablerigid conductor electrode 92 can be formed reliably.

FIG. 21 is a sectional view showing a state in which the firstanisotropically conductive sheet is laminated on both sides of the relayboard in FIG. 12, and FIG. 22 is a partially enlarged view showing thesame.

The anisotropically conductive sheet of a dispersion type is used forthe first anisotropically conductive sheet 22. The material of theinsulating base material, the thickness of the sheet, the material andparticle diameter of the conductive particle P and the like have beendescribed above.

FIG. 23 is a sectional view showing a state in which the relay board andthe first anisotropically conductive sheet in FIG. 21 are laminated onthe board for pitch conversion. In this example, the board 23 for pitchconversion is provided with the connecting electrode 25 constituted bythe terminal electrode 27 for a current and the terminal electrode 28for a voltage making a pair which are to be connected to the sameelectrode 2 to be inspected (the electrode 3 to be inspected) and aredisposed apart from each other. These connecting electrodes 25 aredisposed in accordance with the patterns of the electrodes 2 and 3 to beinspected.

The terminal electrode 27 for a current and the terminal electrode 28for a voltage are electrically connected to the terminal electrode 24through the internal wiring 53, respectively. The rigid conductorelectrode 92 is disposed in accordance with the specific pattern of theconnecting electrode 25 and is positioned just above the connectingelectrode 25.

By using such a relay board, even if the circuit board to be aninspecting target has a small distance between adjacent electrodes to beinspected and has a variation in the height of the electrode to beinspected, it is possible to achieve an electrical connection to therespective electrodes to be inspected in a state in which a necessaryinsulating property for the adjacent electrodes to be inspected ismaintained.

In the inspecting apparatus according to the present invention, thetester side connectors 41 a and 41 b include third anisotropicallyconductive sheets 42 a and 42 b, connector boards 43 a and 43 b, andbase plates 46 a and 46 b as shown in FIG. 1. The same thirdanisotropically conductive sheets 42 a and 42 b as those of the secondanisotropically conductive sheet 26 described above are used. Morespecifically, the third anisotropically conductive sheets 42 a and 42 bare constituted by the conductive path forming portions provided byarranging a large number of conductive particles in the direction of athickness in the insulating elastic polymer material and the insulatingportions for separating the respective conductive path forming portionsfrom each other as shown in FIG. 11.

The connector boards 43 a and 43 b include insulating boards and havepin side electrodes 45 a and 45 b formed at the relay pin unit 31 sideon surfaces thereof as shown in FIGS. 1 and 2.

These pin side electrodes 45 are disposed on lattice points at a certainpitch of 2.54 mm, 1.8 mm, 1.27 mm, 1.06 mm, 0.8 mm, 0.75 mm, 0.5 mm,0.45 mm, 0.3 mm or 0.2 mm, for example, and the arrangement pitch isequal to that of the conductive pin 32 of the relay pin unit 31.

The respective pin side electrodes 45 are electrically connected totester side electrodes 44 a and 44 b through a wiring pattern formed onthe surface of the insulating board and an internal wiring formedtherein.

In case of an inspecting apparatus for carrying out a 4-terminalinspection, these pin side electrodes 45 are constituted by a pin sideelectrode for a current and a pin side electrode for a voltage whichmake a pair so as to be electrically connected to the terminal electrode27 for a current and the terminal electrode 28 for a voltage in theboard 23 for pitch conversion separately and respectively. The pin sideelectrode for a current and the pin side electrode for a voltage aredisposed in positions corresponding to the conductive pin 32 of therelay pin unit 31 which will be described below, respectively.

The relay pin unit 31 has a large number of conductive pins 32 a and 32b provided at a predetermined pitch in parallel in a vertical directionas shown in FIGS. 1, 2, 24 (FIG. 24 shows the relay pin unit 31 a forconvenience of explanation) and 30 to 33. Moreover, the relay pin unit31 includes two insulating plates having first insulating plates 34 aand 34 b serving to insert and support the conductive pins 32 a and 32 band disposed on the side of the circuit board 1 to be inspected andsecond insulating plates 35 a and 35 b disposed on an opposite side tothe side of the circuit board 1 to be inspected which are provided onboth end sides of these conductive pins 32 a and 32 b.

The conductive pin 32 includes a central portion 82 having a largediameter and end portions 81 a and 81 b having smaller diameters asshown in FIG. 25, for example. The first insulating plate 34 and thesecond insulating plate 35 are provided with a through hole 83 in whichthe end portion 81 of the conductive pin 32 is to be inserted. Thethrough hole 83 has a diameter which is larger than the diameter of theend portions 81 a and 81 b of the conductive pin 32 and is smaller thanthe diameter of the central portion 82. Consequently, the conductive pin32 is held so as not to slip off.

The first insulating plate 34 and the second insulating plate 35 arefixed in such a manner that their interval is longer than the length ofthe central portion 82 of the conductive pin 32 through a first supportpin 33 and a second support pin 37 in FIG. 1. Consequently, theconductive pin 32 is held to be vertically movable. The end portion 81of the conductive pin 32 is formed to have a length which is greaterthan the thicknesses of the first insulating plate 34 and the secondinsulating plate 35. Thus, the conductive pin 32 is protruded from atleast one of the first insulating plate 34 and the second insulatingplate 35.

In the relay pin unit, a large number of conductive pins are provided onlattice points at a pitch of 2.54 mm, 1.8 mm, 1.27 mm, 1.06 mm, 0.8 mm,0.75 mm, 0.5 mm, 0.45 mm, 0.3 mm or 0.2 mm, for example.

By setting the arrangement pitch of the conductive pin 32 in the relaypin unit 31 to be equal to that of the terminal electrode 24 provided onthe board 23 for pitch conversion, the board 23 for pitch conversion iselectrically connected to the tester side through the conductive pin 32.

In the relay pin unit 31, moreover, intermediate holding plates 36 a and36 b are provided between the first insulating plates 34 a and 34 b andthe second insulating plates 35 a and 35 b as shown in FIGS. 1 and 24.

First support pins 33 a and 33 b are provided between the firstinsulating plates 34 a and 34 b and the intermediate holding plates 36 aand 36 b. Consequently, the first insulating plates 34 a and 34 b andthe intermediate holding plates 36 a and 36 b are fixed to each other.

Similarly, second support pins 37 a and 37 b are provided between thesecond insulating plates 35 a and 35 b and the intermediate holdingplates 36 a and 36 b. Consequently, the second insulating plates 35 aand 35 b and the intermediate holding plates 36 a and 36 b are fixed toeach other.

A metal such as brass or stainless is used for the materials of thefirst support pin 33 and the second support pin 37.

Although a distance L1 between the first insulating plate 34 and theintermediate holding plate 36 and a distance L2 between the secondinsulating plate 35 and the intermediate holding plate 36 in FIG. 24 arenot particularly restricted, they are preferably equal to or greaterthan 2 mm and are more preferably equal to or greater than 2.5 mm inconsideration of the absorption of a variation in the heights of theelectrodes 2 and 3 to be inspected in the circuit board 1 to beinspected due to the elasticity of each of the first insulating plate34, the intermediate holding plate 36 and the second insulating plate 35as will be described below.

As shown in FIG. 24, a first abutment support position 38A of the firstsupport pin 33 with respect to the intermediate holding plate 36 and asecond abutment support position 38B of the second support pin 37 withrespect to the intermediate holding plate 36 are placed differently fromeach other over an intermediate holding plate projecting surface A ontowhich the inspecting apparatus is projected in the direction of thethickness of the intermediate holding plate (from an upper part toward alower part in FIG. 1).

In this case, the different positions are not particularly restricted.However, it is preferable that the first abutment support position 38Aand the second abutment support position 38B should be formed onlattices over the intermediate holding plate projecting surface A asshown in FIG. 29.

More specifically, as shown in FIG. 29, one second abutment supportposition 38B is provided in a unit lattice region R1 constituted by fourfirst abutment support positions 38A which are adjacent to each otherover the intermediate holding plate projecting surface A. Moreover, onefirst abutment support position 38A is provided in a unit lattice regionR2 constituted by four second abutment support positions 38B which areadjacent to each other over the intermediate holding plate projectingsurface A. In FIG. 29, the first abutment support position 38A isindicated as a black circle and the second abutment support positiongroup 38B is indicated as a white circle.

Herein, one second abutment support position 38B is placed on the centerof a diagonal line Q1 of the unit lattice region R1 in the firstabutment support position 38A, and furthermore, one first abutmentsupport position 38A is placed on the center of a diagonal line Q2 ofthe unit lattice region R2 in the second abutment support position 38B.However, these relative positions are not particularly restricted butare preferably placed differently from each other over the intermediateholding plate projecting surface A onto which the inspecting apparatusis projected in the direction of the thickness of the intermediateholding plate as described above. More specifically, in the case inwhich the positions are not placed like a lattice, such a relativepositional relationship is not restrained. It is sufficient that thepositions are placed differently from each other over the intermediateholding plate projecting surface A onto which the inspecting apparatusis projected in the direction of the thickness of the intermediateholding plate as described above.

In this case, moreover, a distance between the first abutment supportpositions 38A which are adjacent to each other and a distance betweenthe second abutment support positions 38B which are adjacent to eachother are preferably 10 to 100 mm, are more preferably 12 to 70 mm andare particularly preferably 15 to 50 mm.

The materials for forming the first insulating plate 34, theintermediate holding plate 36 and the second insulating plate 35 whichhave a flexibility are used. The flexibility of these plates is asfollows. In the case in which both ends of each of the first insulatingplate 34, the intermediate holding plate 36 and the second insulatingplate 35 are provided horizontally in a support state at an interval of10 cm, it is preferable that a flexure generated by a downwardpressurization at a pressure of 50 kgf should be equal to or smallerthan 0.02% of the widths of these insulating plates and a breakage and apermanent deformation should be prevented from being caused by adownward pressurization at a pressure of 200 kgf.

For the materials of the first insulating plate 34, the intermediateholding plate 36 and the second insulating plate 35, specifically, thereare used insulating materials having a specific resistance of 1×10¹⁰Ω·cm or more, for example, a resin material having a high mechanicalstrength such as a polyimide resin, a polyester resin, a polyamideresin, a phenol resin, a polyacetal resin, a polybutylene terephthalateresin, a polyethylene terephthalate resin, a syndiotactic•polystyreneresin, a polyphenylene sulfide resin, a polyether ethylketone resin, afluorine resin, a polyether nitryl resin, a polyether sulfone resin, apolyallylate resin or a polyamide imide resin, a glass fiber typecomposite resin material such as a glass fiber reinforced epoxy resin, aglass fiber reinforced polyester resin, a glass fiber reinforcedpolyimide resin, a glass fiber reinforced phenol resin or a glass fiberreinforced fluorine resin, a carbon fiber type composite resin such as acarbon fiber reinforced epoxy resin, a carbon fiber reinforced polyesterresin, a carbon fiber reinforced polyimide resin, a carbon fiberreinforced phenol resin or a carbon fiber reinforced fluorine resin, acomposite resin material obtained by filling an epoxy resin, a phenolresin or the like with an inorganic material such as silica, alumina orboron nitride, a composite resin material obtained by containing a meshin the epoxy resin, the phenol resin or the like, and others. Moreover,it is also possible to use a composite plate member constituted bylaminating a plurality of plate members formed by these materials.

While the thickness of each of the first insulating plate 34, theintermediate holding plate 36 and the second insulating plate 35 isproperly selected corresponding to the type of the material constitutingeach of the first insulating plate 34, the intermediate holding plate 36and the second insulating plate 35, it is preferably 1 to 10 mm. Forexample, it is possible to use a plate formed by the glass fiberreinforced epoxy resin and having a thickness of 2 to 5 mm.

For a method of movably supporting the conductive pin 32 on the firstinsulating plate 34 and the second insulating plate 35, it is possibleto employ a method shown in FIGS. 26 to 28 in addition to the methodshown in FIG. 25. In this example, a bending and holding plate 84 isprovided between the first insulating plate 34 and the second insulatingplate 35 as shown.

Moreover, a metallic pin taking a cylindrical shape is used for theconductive pin 32.

As shown in FIG. 26, the bending and holding plate 84 is provided with athrough hole 85 into which the conductive pin 32 is inserted. Theconductive pins 32 are pressed transversely in opposite directions toeach other by setting, as fulcrums, a through hole 83 a formed on thefirst insulating plate 34 and a through hole 83 b formed on the secondinsulating plate 35, and the through hole 85 formed on the bending andholding plate 84, and are bent in the position of the through hole 85 ofthe bending and holding plate 84. Consequently, the conductive pins 32are supported movably in an axial direction.

The intermediate holding plate 36 is provided with a through hole 86having a diameter increased so as not to come in contact with theconductive pin 32, and the conductive pin 32 is inserted in the throughhole 86.

The conductive pin 32 is supported on the first insulating plate 34 andthe second insulating plate 35 in a procedure shown in FIGS. 27( a) to27(c). As shown in FIG. 27( a), the bending and holding plate 84 isprovided in a position in which the through hole 83 a formed on thefirst insulating plate 34 and the through hole 83 b formed on the secondinsulating plate 35, and the through hole 85 of the bending and holdingplate 84 are aligned in an axial direction.

As shown in FIG. 27( b), next, the conductive pin 32 is inserted fromthe through hole 83 a of the first insulating plate 34 to the throughhole 83 b of the second insulating plate 35 via the through hole 85 ofthe bending and holding plate 84.

As shown in FIG. 27( c), subsequently, the bending and holding plate 84is moved in a transverse direction (horizontal direction) which isperpendicular to the axial direction of the conductive pin 32 and theposition of the bending and holding plate 84 is fixed by proper means.Consequently, the conductive pins 32 are pressed transversely in theopposite directions to each other by setting, as fulcrums, the throughhole 83 a of the first insulating plate 34 and the through hole 83 bformed on the second insulating plate 35, and the through hole 85 of thebending and holding plate 84 so that they are bent in the position ofthe through hole 85 of the bending and holding plate 84. Thus, theconductive pin 32 is supported movably in the axial direction.

By such a structure, the conductive pin 32 can be held between the firstinsulating plate 34 and the second insulating plate 35 so as to bemovable in the axial direction and not to slip off, and furthermore, acylindrical pin having a simple structure can be used as the conductivepin 32. Therefore, it is possible to reduce the whole cost of theconductive pin 32 and the members for holding the conductive pin 32.

A position in which the bending and holding plate 84 is to be disposedmay be placed between the first insulating plate 34 and the intermediateholding plate 36.

In the inspecting apparatus according to the present embodiment whichhas such a structure, as shown in FIG. 2, by pressing the base plates 46a and 46 b which are provided on an outermost side at a normal pressureby means of the pressurizing mechanism of a tester through the firstanisotropically conductive sheets 22 a and 22 b, the boards 23 a and 23b for pitch conversion, the second anisotropically conductive sheets 26a and 26 b, the conductive pins 32 a and 32 b, the third anisotropicallyconductive sheets 42 a and 42 b, and the connector boards 43 a and 43 b,the electrodes 2 and 3 in the circuit board 1 to be inspected areconnected electrically to the tester (not shown) and an electricalinspection such as the measurement of an electrical resistance betweenthe electrodes of the circuit board 1 to be inspected is thus carriedout.

The pressure for pressing from the first inspecting jig 11 a and thesecond inspecting jig 11 b on upper and lower sides against the circuitboard to be inspected in the measurement is 100 to 250 kgf, for example.

Referring to FIGS. 30 to 33 (for convenience, only the second inspectingjig 11 b is shown), description will be given to a pressure absorbingfunction and a pressure dispersing function in the case in which bothsides of the circuit board 1 to be inspected are interposed by pressurebetween the first inspecting jig 11 a and the second inspecting jig 11b.

When both sides of the circuit board 1 to be inspected which is aninspecting target are interposed by pressure between the firstinspecting jig 11 a and the second inspecting jig 11 b to carry out anelectrical inspection as shown in FIG. 31, a pressure can be absorbed bythe movement of the conductive pin 32 of the relay pin unit 31 in thedirection of a thickness and the rubber elastic compression of the firstanisotropically conductive sheet 22, the second anisotropicallyconductive sheet 26 and the third anisotropically conductive sheet 42 sothat a variation in the height of the electrode to be inspected in thecircuit board 1 to be inspected can be absorbed to some degree in anearly stage of a pressurization.

The first abutment support position of the first support pin withrespect to the intermediate holding plate and the second abutmentsupport position of the second support pin with respect to theintermediate holding plate are placed differently from each other in theintermediate holding plate projecting surface which is projected in thedirection of the thickness of the intermediate holding plate. When aforce acts in a vertical direction as shown in an arrow of FIG. 32 sothat the circuit board 1 to be inspected which is the inspecting targetis further pressurized between the first inspecting jig 11 a and thesecond inspecting jig 11 b as shown in FIG. 33, therefore, it ispossible to disperse the concentration of a pressure, thereby avoidingthe local concentration of a stress with respect to a variation in theheight of the electrode to be inspected in the circuit board 1 to beinspected, for example, a variation in the height of a solder ballelectrode by the spring elasticities of the first insulating plate 34,the second insulating plate 35 and the intermediate holding plate 36provided between the first insulating plate 34 and the second insulatingplate 35 in the relay pin unit 31 in addition to the rubber elasticcompression of the first anisotropically conductive sheet 22, the secondanisotropically conductive sheet 26 and the third anisotropicallyconductive sheet 42.

More specifically, as shown in FIGS. 32 and 33, the intermediate holdingplate 36 is flexed in the direction of the second insulating plate 35around the first abutment support position 38A of the first support pin33 with respect to the intermediate holding plate 36 (see a portion Esurrounded in a one-dotted chain line of FIG. 33) and the intermediateholding plate 36 is flexed in the direction of the first insulatingplate 34 around the second abutment support position 38B of the secondsupport pin 37 with respect to the intermediate holding plate 36 (see aportion D surrounded in a one-dotted chain line of FIG. 33). Herein,“flex” and “flexing direction” indicate that the intermediate holdingplate 36 is flexed to be protruded in a convex direction and a directionof the protrusion.

Thus, the intermediate holding plate 36 is flexed around the firstabutment support position 38A and the second abutment support position38B in mutually opposite directions. When the circuit board 1 to beinspected which is the inspecting target is further pressurized betweenthe first inspecting jig 11 a and the second inspecting jig 11 b,therefore, the spring elastic force of the intermediate holding plate 36is exhibited.

As shown in a portion B surrounded in a one-dotted chain line of FIG.33, moreover, the protruded part of the conductive path forming portionin the second anisotropically conductive sheet 26 is compressed.Consequently, the height of the conductive pin 32 is absorbed. However,a pressure which cannot be absorbed perfectly by the compression of theprotruded part is added to the first insulating plate 34.

As shown in a portion C surrounded in a one-dotted chain line of FIG.33, accordingly, the first insulating plate 34 and the second insulatingplate 35 are also flexed in the mutually opposite directions in theabutment positions of the first support pin 33 and the second supportpin 37. When the circuit board 1 to be inspected which is the inspectingtarget is further pressurized between the first inspecting jig 11 a andthe second inspecting jig 11 b, therefore, the spring elastic force ofeach of the first insulating plate 34 and the second insulating plate 35is exhibited.

Consequently, a stable electrical contact can be maintained and theconcentration of a stress can further be reduced for each of theelectrodes to be inspected in the circuit board 1 to be inspected whichhave a variation in the heights. Therefore, it is possible to suppressthe local breakage of the first anisotropically conductive sheet 22. Asa result, it is possible to enhance a durability to the repetitive useof the first anisotropically conductive sheet 22. Thus, the number ofexchanges thereof can be decreased and the efficiency of an inspectingwork can be enhanced.

FIG. 34 is the same sectional view as FIG. 30 for explaining anotherembodiment of the inspecting apparatus in accordance with the presentinvention (which shows only a second inspecting jig for convenience),and FIG. 35 is an enlarged sectional view showing a relay pin unit. Theinspecting apparatus has basically the same structure as the inspectingapparatus shown in FIG. 1, and the same components have the samereference numerals. In the inspecting apparatus, a plurality of (threein the present embodiment) intermediate holding plates 36 is providedapart from each other at a predetermined interval between a firstinsulating plate 34 and a second insulating plate 35, and furthermore, aholding plate support pin 39 is disposed between these intermediateholding plates 36 which are adjacent to each other as shown in FIGS. 34and 35.

In this case, in at least one intermediate holding plate 36 b, it isnecessary to place an abutment support position of a holding platesupport pin 39 b to abut on the intermediate holding plate 36 b from onesurface side with respect to the intermediate holding plate 36 b and anabutment support position of a first support pin 33 b, a second supportpin 37 b or the holding plate support pin 39 b to abut on theintermediate holding plate 36 b from the other surface side with respectto the intermediate holding plate 36 b differently from each other overan intermediate holding plate projecting surface which is projected inthe direction of the thickness of the intermediate holding plate 36 b.

Most preferably, in all of the intermediate holding plates 36 b, theabutment support position of the holding plate support pin 39 b to abuton the intermediate holding plate 36 b from one surface side withrespect to the intermediate holding plate 36 b and the abutment supportposition of the first support pin 33 b, the second support pin 37 b orthe holding plate support pin 39 b to abut on the intermediate holdingplate 36 b from the other surface side with respect to the intermediateholding plate 36 b are placed differently from each other over theintermediate holding plate projecting surface which is projected in thedirection of the thickness of the intermediate holding plate 36 b.

In this case, the “different position” can be set to be the same as therelative position described based on the relationship between the firstabutment support position 38A of the first support pin 33 and theintermediate holding plate 36 and the second abutment support position38B of the second support pin 37 and the intermediate holding plate 36in the embodiment described above, which will not be described indetail.

In the present example, in an upper one of the three intermediateholding plates 36 b, an abutment support position 39A of the holdingplate support pin 39 b to abut on the intermediate holding plate 36 bfrom one surface side with respect to the intermediate holding plate 36b and an abutment support position 38A of the first support pin 33 b toabut on the intermediate holding plate 36 b from the other surface sidewith respect to the intermediate holding plate 36 b are placeddifferently from each other over the intermediate holding plateprojecting surface which is projected in the direction of the thicknessof the intermediate holding plate 36 b.

In a central one of the three intermediate holding plates 36 b,moreover, the abutment support position 39A of the holding plate supportpin 39 b to abut on the intermediate holding plate 36 b from one surfaceside with respect to the intermediate holding plate 36 b and theabutment support position 39A of the holding plate support pin 39 b toabut on the intermediate holding plate 36 b from the other surface sidewith respect to the intermediate holding plate 36 b are placeddifferently from each other over the intermediate holding plateprojecting surface which is projected in the direction of the thicknessof the intermediate holding plate 36 b.

In a lower one of the three intermediate holding plates 36 b, moreover,the abutment support position 39A of the holding plate support pin 39 bto abut on the intermediate holding plate 36 b from one surface sidewith respect to the intermediate holding plate 36 b and the abutmentsupport position 38B of the second support pin 37 b to abut on theintermediate holding plate 36 b from the other surface side with respectto the intermediate holding plate 36 b are placed differently from eachother over the intermediate holding plate projecting surface which isprojected in the direction of the thickness of the intermediate holdingplate 36 b.

By such a structure, a spring elasticity is further exhibited by theseintermediate holding plates 36 so that the concentration of a pressurecan be dispersed and the local concentration of a stress can further beavoided for a variation in the height of the electrode to be inspectedin the circuit board 1 to be inspected. Consequently, the local breakageof an anisotropically conductive sheet can be suppressed. As a result, adurability to the repetitive use of the anisotropically conductive sheetcan be enhanced. Thus, the number of exchanges of the anisotropicallyconductive sheet can be decreased so that the efficiency of aninspecting work can be enhanced.

The number of the intermediate holding plates 36 is preferably two ormore and is not particularly restricted.

In the case in which the bending and holding plate 84 for holding theconductive pin 32 is used, moreover, it can be disposed between thesecond insulating plate 35 and the intermediate holding plate 36,between the first insulating plate 34 and the intermediate holding plate36 or between the two intermediate holding plates 36 depending on thecircumstances.

While the embodiments of the present invention have been describedabove, the present invention is not restricted to these embodiments butvarious changes and modifications can be made without departing from thescope thereof.

For example, the circuit board 1 to be inspected may be a semiconductorintegrated circuit device such as a package IC, an MCM or a CSP or acircuit device formed on a wafer as well as a printed circuit board.Moreover, the printed circuit board may be a single-sided printedcircuit board in place of a double-sided printed circuit board.

The first inspecting jig 11 a and the second inspecting jig 11 b do notneed to be always identical to each other but may be different from eachother in materials to be used, the structures of members and the like.

The tester side connector may be constituted by laminating circuitboards such as connector boards and anisotropically conductive sheets.

While there have been used the second anisotropically conductive sheet26 and the third anisotropically conductive sheet 42 which areconstituted by the conductive path forming portions extended in thedirection of the thickness and the insulating portion for insulatingthese conductive path forming portions from each other and in which theconductive particles are contained in only the conductive path formingportions and are thus dispersed nonuniformly in the planar direction andthe conductive path forming portions are protruded from either side ofthe sheet in the examples described above, this is not alwaysrestricted.

As shown in FIGS. 1, 2, 30, 31, 33 and 34, furthermore, the support pin49 may be provided between the connector board 43 and the base plate 46in the tester side connector 41. By these support pins 49, it is alsopossible to give the function of dispersing a surface pressure in thesame manner as the function given from the first support pin 33 and thesecond support pin 37 (in FIG. 18, the first support pin 33, the secondsupport pin 37 and the holding plate support pin 39). In order to givethe function of dispersing a surface pressure, it is preferable that theposition of the support pin 49 and that of the second support pin 37should be placed in such a manner that they are different from eachother in the planar direction.

Specific examples and comparative examples according to the presentinvention will be described below.

Example 1

There was fabricated an inspecting apparatus for inspecting thefollowing circuit board for estimation shown in FIG. 1 which is adaptedto the inspecting portion of a rail delivery type circuit boardautomatic inspecting machine (manufactured by Nidec Read Corporation,trade name: STARREC V5).

(1) Circuit Board 1 for Estimation

A circuit board 1 for estimation which has the following specificationwas prepared.

Dimension: 100 mm (length)×100 mm (width)×0.8 mm (thickness)

Number of electrodes to be inspected on upper surface side: 3600

Diameter of electrode to be inspected on upper surface side: 0.25 mm

Minimum arrangement pitch of electrode to be inspected on upper surfaceside: 0.4 mm

Number of electrodes to be inspected on lower surface side: 2600

Diameter of electrode to be inspected on lower surface side: 0.25 mm

Minimum arrangement pitch of electrode to be inspected on lower surfaceside: 0.4 mm

(2) First Anisotropically Conductive Sheet 22

There was fabricated the following first anisotropically conductivesheet in which a conductive particle was arranged in the direction of athickness and was uniformly dispersed in a planar direction.

Dimension: 110 mm×110 mm, thickness of 0.05 mm

Conductive particle: material; nickel particle subjected to gold platingtreatment, mean particle diameter; 20 μm, content; 18 volume %

Elastic polymer substance: material; silicone rubber (hardness of 40)

(3) Board 23 for Pitch Conversion

There were formed a total number of 7200 circular through holes having adiameter of 0.1 mm and penetrating in the direction of the thickness ofa laminating material (manufactured by Matsushita Electric Works, Ltd.,trade name: R-1766) obtained by providing a metallic thin layer formedof copper having a thickness of 18 μm over the whole both sides of aninsulating board formed of a glass fiber reinforced type epoxy resin andhaving a thickness of 0.5 mm respectively by means of a numericalcontrol type drilling device on the laminating material.

In this case, two through holes make a set and are formed in positionscorresponding to the electrode to be inspected on the upper surface sideof the circuit board for estimation, and a set of through holes areformed with a gap of 0.1 mm provided therebetween (more specifically, itimplies to set a gap of 0.1 mm between a through hole A=0.1 mm and athrough hole B=0.1 mm).

Subsequently, the laminating material provided with the through holeswas subjected to a nonelectrolytic plating treatment by using an EDTAtype copper plating solution, thereby forming a copper plated layer onthe internal wall of each of the through holes, and furthermore, wassubjected to an electrolytic copper plating treatment by using a coppersulfate plating solution, thereby forming, in each of the through holes,a cylindrical via hole having a thickness of approximately 10 μm whichelectrically connects the metallic thin layers on the surface of thelaminating material to each other.

Then, a dry film resist (manufactured by TOKYO OHKA KOGYO CO., LTD.,trade name: FP-225) having a thickness of 25 μm was laminated on themetallic thin layer of the surface of the laminating material to form aresist layer, and furthermore, a protecting seal was disposed on themetallic thin layer at the other surface side of the laminatingmaterial. A photomask film was disposed on the resist layer and theresist layer was subjected to an exposing treatment by using a parallelray exposing machine (manufactured by ORC SEISAKUSHO) and a developingtreatment was thereafter carried out, thereby forming a resist patternfor etching. Subsequently, the metallic thin layer on a surface havingthe resist pattern formed thereon was subjected to an etching treatment,thereby forming, on the surface of the insulating board, 7200 circularconnecting electrodes having a diameter of 60 μm and a pattern wiringportion having a width of 100 μm for electrically connecting each of theconnecting electrodes to a via hole and then removing the resistpattern.

Next, a dry film resist (manufactured by TOKYO OHKA KOGYO CO., LTD.,trade name: FP-225) having a thickness of 25 μm was laminated to form aresist layer on a surface at the side where the connecting electrode andthe pattern wiring portion in the laminating material were provided, anda photomask film was disposed on the resist layer and the resist layerwas subjected to an exposing treatment by using a parallel ray exposingmachine (manufactured by ORC SEISAKUSHO), and a developing treatment wasthen carried out, thereby forming 7200 circular openings having adiameter of 60 μm which exposed the respective connecting electrodes.

A copper sulfate plating solution was used and the respective connectingelectrodes were subjected to an electrolytic copper plating treatment byusing the metallic thin layer on the other surface side of thelaminating material as a common electrode, thereby forming 7200connecting electrodes. Subsequently, the resist pattern was removed.

Subsequently, the protecting seal provided on the metallic thin layer atthe other surface side of the laminating material was removed and thedry film resist (manufactured by TOKYO OHKA KOGYO CO., LTD., trade name:FP-225) having a thickness of 25 μm was laminated on the metallic thinlayer of the same surface, thereby forming a resist layer. Then, thephotomask film was disposed on the resist layer and the resist layer wassubjected to the exposing treatment by using the parallel ray exposingmachine (manufactured by ORC SEISAKUSHO), and the developing treatmentwas thereafter carried out, thereby forming a resist pattern for etchingon the metallic thin layer in the laminating material.

Next, the protecting seal was provided on a surface at the side wherethe connecting electrode of the laminating material was formed and theetching treatment was then performed to form 7200 terminal electrodesand a pattern wiring portion for electrically connecting each of theterminal electrodes to a via hole on the back face of the insulatingboard and to remove the resist pattern.

Thereafter, a dry film solder resist (manufactured by Nichigo-MortonCo., Ltd., trade name: Confomask 2015) having a thickness of 38 μm waslaminated to form an insulating layer on the back face of the insulatingboard having the terminal electrodes and the pattern wiring portionformed thereon, and the photomask film was disposed on the insulatinglayer and the insulating layer was thereafter subjected to the exposingtreatment by using the parallel ray exposing machine (manufactured byORC SEISAKUSHO), and subsequently, the developing treatment was carriedout. Thus, there were formed 7200 openings having a diameter of 0.4 mmfrom which the electrodes are exposed.

As described above, the board 23 for pitch conversion was fabricated. Inthe board 23 for pitch conversion, a lengthwise and crosswise dimensionwas 120 mm×160 mm, a thickness was 0.5 mm, a diameter of a portionexposed from the surface of the insulating layer of the connectingelectrode 25 was approximately 60 μm, a protrusion height from thesurface of the insulating layer of the connecting electrode 25 wasapproximately 30 μm, a distance between the connecting electrodes 25making a pair was 60 μm, a diameter of the terminal electrode 24 was 0.4mm, and an arrangement pitch of the terminal electrode 24 was 0.75 mm.

In the same manner as described above, moreover, there was fabricatedthe board 23 b for pitch conversion for the second inspecting jig 11 bwhich had 5200 connecting electrodes 25 on a surface and 5200 terminalelectrodes 24 on a back face.

In the board 23 b for pitch conversion, a lengthwise and crosswisedimension is 120 mm×160 mm, a thickness is 0.5 mm, a diameter of aportion exposed from the surface of the insulating layer in theconnecting electrode 25 is approximately 60 μm, a protrusion height fromthe surface of the insulating layer in the connecting electrode 25 isapproximately 30 μm, a distance between the connecting electrodes makinga pair is 60 μm, a diameter of the terminal electrode 24 is 0.4 mm, andan arrangement pitch of the terminal electrode 24 is 0.75 mm.

(4) Relay Board 29

3600 circular through holes in total which have a diameter of 0.3 mm andpenetrate in the direction of a thickness of a laminating materialformed by a bismaleimide triazine resin including a copper foil on bothsides and having a thickness of 0.1 mm (Mitsubishi Gas Chemical Company,Inc.: Material for BT resin printed wiring board CCL-HL832) respectivelywere formed over whole both sides of the laminating material by means ofa numerical control type drilling device.

Addition type liquid silicone rubber was filled in the through hole byusing a squeegee, and subsequently, a heat treatment was carried out ata temperature of 100° C. for 90 minutes over a board formed of a resinin which the addition type liquid silicone rubber was disposed in thethrough hole, thereby forming, in the through hole, a board materialincluding an insulating elastic film constituted by the silicone rubber.

Next, a metal mask for a laser processing which includes an openingpattern having a diameter of 60 μm in a position corresponding to theelectrode to be inspected in the circuit board to be inspected waslaminated on one surface side of the board material including theinsulating elastic film, and the laminated product was disposed on aprocessing stage of a CO₂ laser processing machine “Impact L-500”(manufactured by SUMITOMO HEAVY INDUSTRIES, LTD.), and a laser beam wasirradiated on the following conditions from the side on which the metalmask for a laser processing was laminated, thereby forming a throughhole having a diameter of approximately 60 μm on the insulating elasticfilm.

<Irradiating Condition of Laser Beam>

Laser type: TEA-CO₂

Frequency (number of pulses per second): 50 Hz

Pattern (beam width): 0.9×1.9 mm

Scanning speed (stage moving speed in laser processing machine): 814mm/min

Voltage (excited voltage): 20 kV

Energy density (laser irradiation energy per unit area): 11 J/cm²

Number of scans: four

Then, the metal mask for a laser processing which was laminated wasremoved and a nonelectrolytic plating treatment was carried out by usingan EDTA type copper plating solution over a board material in which athrough hole was formed on an insulating elastic film. Consequently,there was obtained a laminating board material in which a copper platedlayer was formed on an internal wall of each through hole and a surfaceof the board material.

Next, a dry film resist having a thickness of 25 μm was laminated onboth sides of the laminating board material subjected to the copperplated layer, thereby forming a resist layer.

Then, a pattern opening having a diameter of 60 μm was formed in thethrough hole portion provided on the insulating elastic film.

Furthermore, an electrolytic copper plating treatment was carried out byusing a copper sulfate plating solution, thereby forming a cylindricalvia hole having a diameter of approximately 60 μm which serves toelectrically connect respective metallic thin layers in the laminatingmaterial and an electrode portion having a diameter of 60 μm and athickness of approximately 25 μm which was provided in the patternopening of the dry film and was linked to the via hole.

Subsequently, the laminating material forming the electrode portion wasimmersed in a sodium hydroxide solution at 45° C. for two minutes toremove the dry film layer, and a ferric chloride type etchant was thenused to carry out an etching treatment at 50° C. for 30 seconds, therebyremoving the copper layer on the surface of the laminating material.Consequently, adjacent electrode structures constituted by therespective electrode portions and the through holes were electricallyinsulated from each other to obtain the relay board 29 a for the firstinspecting jig 11 a.

In the same manner as described above, moreover, there was fabricatedthe relay board 29 b for the second inspecting jig 11 b having 5200electrode structures.

The relay board including the electrode structure (the rigid conductorelectrode) thus obtained was as follows.

[Relay Board 29 a]

Thickness of insulating board 100 μmDiameter of insulating elastic film 300 μmThickness of insulating elastic film 100 μmDimension of electrode portion of electrode structure diameter of 60μm×thickness of 150 μmDimension of through hole portion of electrode structure diameter of 60μm×thickness of 100 μmDistance between electrode structures making a pair 60 μmNumber of electrode structures 7200

[Relay Board 29 b]

Thickness of insulating board 100 μmDiameter of insulating elastic film 300 μmThickness of insulating elastic film 100 μmDimension of electrode portion of electrode structure diameter of 60μm×thickness of 150 μmDimension of through hole portion of electrode structure diameter of 60μm×thickness of 100 μmDistance between electrode structures making a pair 60 μmNumber of electrode structures 5200

(5) Circuit Board Side Connector 21

The board 23 for pitch conversion had one surface side where the pair offirst anisotropically conductive sheets 22 were disposed to interposethe relay board 29 therebetween, and a back face side provided with thesecond anisotropically conductive sheet 26 constituted by ananisotropically conductive sheet of an uneven distribution type whichincludes a large number of conductive path forming portions extended inthe direction of a thickness and an insulating portion for insulatingthem from each other and in which the conductive path forming portionwas protruded from either side. Thus, the circuit board side connector21 was obtained.

The second anisotropically conductive sheet 26 took the shape shown inFIG. 11. More specifically, the following structure was used.

[Second Anisotropically Conductive Sheet 26]

Dimension: 110 mm×150 mmThickness of conductive path forming portion: 0.6 mmOutside diameter of conductive path forming portion: 0.35 mmProtrusion height of conductive path forming portion: 0.05 mmConductive particle: material; nickel particle subjected to gold platingtreatment, mean particle diameter; 35 μm, content of conductive particlein conductive path forming portion; 30 volume %Elastic polymer substance: material; silicone rubber, hardness; 30

(W₂/D₂=17) (6) Relay Pin Unit 31

For the materials of the first insulating plate 34, the intermediateholding plate 36 and the second insulating plate 35, there were used aninsulating material having a specific resistance of 1×¹⁰ Ω·cm or moreand a material formed by a glass fiber reinforced epoxy resin and havinga thickness of 1.9 mm.

Then, the first insulating plate 34, the intermediate holding plate 36and the second insulating plate 35 were fixed and supported by means ofthe first support pin 33 (a diameter of 2 mm and a length of 36.3 mm)and the second support pin 37 (a diameter of 2 mm and a length of 3 mm)in such a manner that the distance L1 between the first insulating plate34 and the intermediate holding plate 36 is 36.3 mm and the distance L2between the second insulating plate 35 and the intermediate holdingplate 36 is 3 mm, and furthermore, the conductive pin 32 in FIG. 25having the following structure was disposed movably in the through hole83 (a diameter of 0.4 mm) between the first insulating plate 34 and thesecond insulating plate 35.

[Conductive Pin]

Material: brass subjected to gold plating treatmentDimension of the tip portion 81 a: outside diameter of 0.35 mm, totallength of 2.1 mmDimension of the central portion 32: outside diameter of 0.45 mm, totallength of 41 mmDimension of the base end 81 b: outside diameter of 0.35 mm, totallength of 2.1 mm

In this case, the first abutment support position 38A of the firstsupport pin 33 with respect to the intermediate holding plate 36 and thesecond abutment support position 38B of the second support pin 37 withrespect to the intermediate holding plate 36 were arranged like alattice as shown in FIG. 29. A distance between the first abutmentsupport positions 38A which are adjacent to each other and a distancebetween the second abutment support positions 38B which are adjacent toeach other were set to be 17.5 mm.

(7) Tester Side Connector 41

The tester side connector 41 was constituted by the thirdanisotropically conductive sheet 42, the connector board 43 and the baseplate 46 as shown in FIG. 1. The third anisotropically conductive sheet42 to be used was the same as the second anisotropically conductivesheet 26 described above.

Performance Test

1. Measurement of Lowest Press Pressure The fabricated inspectingapparatus was set into the inspecting portion of the rail delivery typecircuit board automatic inspecting machine “STARREC V5” and the circuitboard 1 for estimation which was prepared for the inspecting apparatuswas set to stepwise change the press pressure of the rail delivery typecircuit board automatic inspecting machine “STARREC V5” within a rangeof 100 to 210 kgf and to measure, by an electrode for measuring avoltage, a conducting resistance value in the application of a currentof 1 milliampere through an electrode for supplying a current for theelectrode to be inspected in the circuit board 1 for estimation 10 timesfor each press pressure condition.

An inspecting point having the measured conducting resistance value of10Ω or more (which will be hereinafter referred to as an “NG inspectingpoint”) was decided to be a conducting failure, and a rate of the NGinspecting point in a total inspecting point (which will be hereinafterreferred to as an “NG inspecting point rate”) was calculated and thelowest press pressure having an NG inspecting point rate of 0.01% orless was set to be the lowest press pressure.

In the measurement of the conducting resistance value, the measurementof one conducting resistance value was completed and the press pressurerelated to the measurement was then released to return the inspectingapparatus into a non-pressurization state, and a next measurement forthe conducting resistance value was carried out by causing a presspressure having a predetermined magnitude to act again.

The number of electrodes to be inspected on an upper surface of thecircuit board 1 for estimation was 3600 and the number of electrodes tobe inspected on a lower surface was 2600, and the measurement wascarried out 10 times on each press pressure condition. Therefore, the NGinspecting point rate indicates the rate of the NG inspecting pointoccupying 62000 inspecting points which are calculated by an equation of(3600+2600)×10=62000.

In this case, “the lowest press pressure is low” implies that theelectrical inspection of the circuit board to be inspected can becarried out at a low press pressure. In the inspecting apparatus, if apressurizing pressure in the inspection can be set to be low, it ispossible to prevent a deterioration in the circuit board to beinspected, the anisotropically conductive sheet and the circuit boardfor an inspection from being caused by the pressurizing pressure in theinspection, and furthermore, to use a component having a low durabilitystrength as a member constituting the inspecting apparatus.Consequently, the structure of the inspecting apparatus can be reducedto be compact. As a result, it is possible to achieve an enhancement inthe durability of the inspecting apparatus and a reduction in themanufacturing cost of the inspecting apparatus. Therefore, it ispreferable that the lowest press pressure should be small.

The result of the measurement for the lowest press pressure is shown inTable 1.

2. Measurement of Durability of Anisotropically Conductive Sheet

The fabricated inspecting apparatus was set into the inspecting portionof the rail delivery type circuit board automatic inspecting machine“STARREC V5” and the circuit board 1 for estimation which was preparedfor the inspecting apparatus was set to repeat a work for carrying out apressurization at a predetermined number of times on the press pressurecondition of the rail delivery type circuit board automatic inspectingmachine “STARREC V5” to be 130 kgf, and then measuring a conductingresistance value in the application of a current of 1 milliamperethrough the electrode for supplying a current 10 times on the conditionof the press pressure of 130 kgf for the electrode to be inspected inthe circuit board 1 for estimation and thereafter performing thepressurization at a predetermined number of times, and measuring theconducting resistance value 10 times through the electrode for measuringa voltage in the same manner.

The inspecting point (NG inspecting point) having the measuredconducting resistance value of 10Ω or more was decided to be aconducting failure and the rate of the NG inspecting point in the totalinspecting point (NG inspecting point rate) was calculated.

Subsequently, a pressurization was carried out at a predetermined numberof times on the same conditions as described above except that theanisotropically conductive sheet in the inspecting apparatus wasreplaced with a new one and the press pressure condition was changed to150 kgf, and thus, the NG inspecting point rate was calculated by thesame method as described above.

In the measurement of the conducting resistance value related to thedurability of the anisotropically conductive sheet, the measurement ofone conducting resistance value was completed and the press pressurerelated to the measurement was then released to return the inspectingapparatus into a non-pressurization state, and a next measurement forthe conducting resistance value was carried out by causing a presspressure having a predetermined magnitude to act again.

In the inspecting apparatus, it is practically required that the NGinspecting point rate is equal to or lower than 0.01%. In other words,in some cases in which the NG inspecting point rate is higher than0.01%, there is obtained an erroneous inspection result that a circuitboard to be inspected which is a good product is decided to be adefective product. For this reason, there is a possibility that acircuit board might not be electrically inspected with a highreliability.

The result of the measurement for the durability of the anisotropicallyconductive sheet is shown in Table 2.

3. Estimation of Insulating Property

In the following manner, an insulation resistance between the connectingelectrodes 25 making a pair of the board 23 for pitch conversion in thecircuit board side connector 21 (the terminal electrode 27 for a currentand the terminal electrode 28 for a voltage) was estimated.

For the estimation of an insulating property between the connectingelectrodes, there was used a glass epoxy board which has a length of 100mm in a longitudinal direction, a length of 100 mm in a transversedirection and a thickness of 0.8 mm and has a surface subjected toinsulating coating.

The fabricated inspecting apparatus was set into the inspecting portionof the rail delivery type circuit board automatic inspecting machine“STARREC V5” and the glass epoxy board was set into the inspectingapparatus. Then, the press pressure of the rail delivery type circuitboard automatic inspecting machine “STARREC V5” was changed stepwisewithin a range of 100 to 210 kgf. Thereafter, an insulation resistancebetween the connecting electrodes 25 provided in the board 23 a forpitch conversion for the first inspecting jig 11 a and making each pairwas measured 10 times for each press pressure condition.

More specifically, the conducting resistance value of the connectingelectrodes 25 making a pair was measured while a current of 1milliampere was applied through the terminal electrode 24 correspondingto the connecting electrodes 25 making the pair. Consequently, theinsulation resistance value was obtained. The connecting electrode pairin which the measured insulation resistance value is equal to or greaterthan 100Ω was decided to be an excellent insulation, and a rate ofpoints decided to be the excellent insulation to the total number ofinspecting points (which will be hereinafter referred to as an“insulating property passing grade rate”) was thus calculated.

7200 connecting electrodes 25 in the board 23 a for pitch conversion inthe first inspecting jig 11 a made 3600 pairs. In other words, 3600connecting electrode pairs were present and the measurement was carriedout 10 times on each press pressure condition. Therefore, the insulatingproperty passing grade rate specifically indicates a rate of NGinspecting points occupying 36000 inspecting points calculated by anequation of (3600)×10=36000.

In the inspecting apparatus, it is practically required that theinsulating property passing grade rate is equal to or higher than 99.9%.More specifically, in the case in which the insulating property passinggrade rate is lower than 99.9%, a leakage current flows from theconnecting electrode to be used as the electrode for supplying a currentto the connecting electrode to be used as an electrode for measuring avoltage in the inspection. In some cases, consequently, there isobtained such an erroneous inspection result that a circuit board to beinspected which is an excellent product is decided to be a defectiveproduct. For this reason, there is a possibility that an electricalinspection for a circuit board having a high reliability cannot becarried out.

The result of the estimation for the insulating property is shown inTable 3.

Example 2

The relay board 29 in the inspecting apparatus according to the example1 was changed into that shown in FIG. 12. First of all, the relay board29 a for the first inspecting jig 11 a having 7200 electrode structureswas manufactured in the following manner.

There was prepared the laminating material 90A (manufactured by NipponSteel Chemical Co., Ltd.: Espanex LC18-50-00NE) obtained by integrallylaminating the metal layer 93A formed of copper having a thickness of 18μm over one surface of the insulating board 91 formed of a liquidcrystal polymer having a thickness of 50 μm (FIG. 14), and a dry filmresist was laminated on the metal layer in the laminating material toform a resist film.

Subsequently, the resist film thus formed was subjected to an exposingtreatment and a developing treatment so that a circular pattern holehaving a diameter of 40 μm was formed on the resist film in accordancewith a pattern corresponding to the electrode to be inspected on theupper surface side in the circuit device for estimation. Then, the metallayer 93A was subjected to an etching treatment so that the opening 93Khaving the same pattern as the pattern hole of the resist film wasformed on the metal layer 93A and the resist film was thereafter removed(FIG. 15).

Subsequently, the insulating board 91 in the laminating material wassubjected to a laser processing by using a CO₂ laser processing machinethrough the opening 93K formed on the metal layer 93A so that thethrough hole 91H communicating with the opening 93K of the metal layer93A was formed.

Then, the internal wall surface of the through hole 91H of theinsulating board 91 was subjected to a nonelectrolytic copper platingtreatment, and furthermore, was subjected to an electrolytic copperplating treatment by using the metal layer 93A to be a common electrode.Consequently, the cylindrical metallic thin layer 93B formed of copperhaving a thickness of 5 μm was provided to cover the internal wallsurface of the through hole 91H of the insulating board 91 and theopening edge of the metal layer 93A. Thus, the composite laminatingmaterial 90B shown in FIG. 17 was manufactured. The through hole 91Hobtained after forming the metallic thin layer had a diameter ofapproximately 30 μm.

Next, a dry film resist having a thickness of 25 μm was laminated oneach of both sides of the composite laminating material 90B (the surfaceof the metal layer 93A formed on one surface of the insulating board 91and the other surface of the insulating board 91) and was subjected tothe exposing treatment and the developing treatment. Consequently, therewas formed the resist film 94 provided with the circular pattern hole94H having a diameter of 50 μm in accordance with the pattern of theterminal portion 92 b in the rigid conductor electrode 92 to be formedas shown in FIG. 18. Then, the electrolytic plating treatment wascarried out by using a plating solution having nickel sulfaminatedissolved therein with the metal layer 93A to be a common electrode sothat the rigid conductor electrode 92 formed of nickel was formed asshown in FIG. 19.

Thereafter, the surface of the terminal portion 92 b of the rigidconductor electrode 92 was polished to flatten the surface of theterminal portion 92 b of the rigid conductor electrode 92 and to causethe thickness of the terminal portion 92 b to be equal to that of theresist film 94. Subsequently, the resist film 94 was removed from bothsides of the composite laminating material 90B and the compositelaminating material 90B was thereafter subjected to the etchingtreatment at 60° C. for 3 hours by using an etchant having ferricchloride dissolved therein. Thus, the metal layer 93A and the metallicthin layer 93B were removed so that the relay board 29 a wasmanufactured.

The relay board 29 a thus obtained will be described. In the relay board29 a, a material is a liquid crystal polymer, a lengthwise and crosswisedimension is 190 mm×130 mm, a thickness d is 50 μm, the through hole 91Hhas a diameter r1 of 40 μm, the total number of the rigid conductorelectrodes 92 is 7200, the drum portion 92 a has a diameter r2 of 30 μm,the terminal portion 92 b has a diameter r3 of 50 μm, the drum portion92 a has a length L of 73 μm, a moving distance (L−d) of the rigidconductor electrode 92 is 23 μm, and a distance between the rigidconductor electrodes 92 making a pair is 70 μm.

In the same manner as described above, moreover, there was manufacturedthe relay board 29 b for the second inspecting jig 11 b having 5200rigid conductor electrodes 92.

The relay board 29 b thus obtained will be described. In the relay board29 b, a material is a liquid crystal polymer, a lengthwise and crosswisedimension is 190 mm×130 mm, a thickness d is 50 μm, the through hole 91Hhas a diameter r1 of 40 μm, the total number of the rigid conductorelectrodes 92 is 7200, the drum portion 92 a has a diameter r2 of 30 μm,the terminal portion 92 b has a diameter r3 of 50 μm, the drum portion92 a has a length L of 73 μm, a moving distance (L−d) of the rigidconductor electrode 92 is 23 μm, and a distance between the rigidconductor electrodes 92 making a pair is 70 μm.

The inspecting apparatus was constituted in the same manner as in theexample 1 except that the relay boards 29 a and 29 b described abovewere used in place of the relay boards 29 a and 29 b in the example 1.Referring to the inspecting apparatus, there were carried out themeasurement of the lowest press pressure, the measurement of thedurability of the anisotropically conductive sheet and the estimation ofthe insulating property described above.

Results are shown in the Tables 1 to 3.

Comparative Example 1

In place of the relay pin unit 31 described above, conventional relaypin units 131 a and 131 b shown in FIG. 36 were used. More specifically,an inspecting apparatus having the same structure as that in the example1 was fabricated except that there was provided a relay pin unit havinga large number of conductive pins 132 a and 132 b (8000 pins) arrangedon lattice points at a certain pitch (a pitch of 2.54 mm) and insulatingplates 134 a and 134 b for supporting the conductive pins 132 a and 132b movably in a vertical direction.

Referring to the inspecting apparatus for a comparison thus fabricated,the lowest press pressure and the durability of the anisotropicallyconductive sheet were measured by the same method as that in the example1.

The result of the measurement of the lowest press pressure is shown inthe Table 1 and the result of the measurement for the durability of theanisotropically conductive sheet is shown in the Table 2.

Comparative Example 2

In the inspecting apparatus according to the example 1, a firstanisotropically conductive sheet 22 formed by an anisotropicallyconductive elastomer sheet of a dispersion type having a thickness of100 μm was disposed in place of the relay board 29 in the circuit boardside connector 21 and the pair of first anisotropically conductivesheets 22 having a thickness of 50 μm which were provided to interposethe relay board 29 therebetween, and an insulation resistance betweenconnecting electrodes 25 making a pair was estimated by the methoddescribed above.

A result of the estimation of the insulating property is shown in theTable 3.

TABLE 1 Lowest Press press pressure NG inspecting point rate (%)pressure (kgf) 100 110 130 150 180 210 (kgf) Example 1 0.30 0.03 0 0 0 0130 Example 2 0.20 0.04 0 0 0 0 130 Comparative 3.5 2.7 0.3 0.01 0 0 180example 1

TABLE 2 Number of presses NG inspecting point rate (%) (number of times)1 1000 5000 10000 30000 Example 1 Press pressure 0 0 0 0 0.4 130 kgfPress pressure 0 0 0 0.06 0.6 150 kgf Example 2 Press pressure 0 0 0 00.3 130 kgf Press pressure 0 0 0 0.04 0.5 150 kgf Comparative Presspressure 0 0 0.05 0.32 1.4 example 1 150 kgf Press pressure 0 0.02 0.150.28 1.9 180 kgf

TABLE 3 Estimation Press of pressure Insulating property passing graderate (%) insulating (kgf) 100 110 130 150 180 210 property Example 199.9%< 99.9%< 99.9%< 99.9%< 99.9%< 99.9%< Excellent insulating propertyExample 2 99.9%< 99.9%< 99.9%< 99.9%< 99.9%< 99.9%< Excellent insulatingproperty Comparative 97.8%  97.5%  96.3%  96.2%  95.7%  95.7%  Poorexample 2 insulating property

As is apparent from the Table 1 and the Table 2, each of the inspectingapparatuses according to the example 1 and the example 2 had the lowestpress pressure which is lower and also had the durability of theanisotropically conductive sheet which is considerably enhanced ascompared with the inspecting apparatuses according to the comparativeexamples.

As is apparent from the result in the Table 3, each of the inspectingapparatuses according to the example 1 and the example 2 rarely has thegeneration of a leakage current between the connecting electrodes.Accordingly, it is possible to electrically inspect a circuit board witha high reliability.

1. A relay board that includes a board through which a plurality ofrigid conductor electrodes penetrate, wherein the plurality of rigidconductor electrodes is held to be movable in a direction of a thicknessof the board, the board has an insulating property and a plurality ofthrough holes is formed on the board, the rigid conductor electrodeincludes a drum portion inserted in the through holes and a terminalportion formed on each end of the drum portion, each having a largerdiameter than a diameter of the through hole, and the rigid conductorelectrode is held in the through hole of the board so as to be movablein the direction of the thickness of the board such that the distancebetween the terminal portion and an opening of the through hole changes.2. The relay board according to claim 1, wherein a plurality of throughholes is formed on the board, an insulating portion formed by apolymeric elastic body is formed in the through holes, and the rigidconductor electrode penetrates through the insulating portion and isheld to be movable in the direction of the thickness of the board bymeans of the insulating portion.
 3. A circuit board side connector thatincludes: the relay board according to claim 1; a pair of firstanisotropically conductive sheets disposed on one surface side and theother surface side of the relay board and having a conductive particlearranged in a direction of a thickness and distributed uniformly in aplanar direction; a board for pitch conversion which converts anelectrode pitch between one of surface sides of the board and the othersurface side; and a second anisotropically conductive sheet provided ona reverse side to the circuit board to be inspected in the board forpitch conversion.
 4. The relay board according to claim 1, wherein theboard is comprised of a material having a higher mechanical strengththan materials formed by a composite resin material such as a glassfiber reinforced polyimide resin, a glass fiber reinforced epoxy resin,or a glass fiber reinforced bismaleimide triazine resin.